1.While the total enrollment of public elementary and secondary schools in Sondland is one percent higher this academic year than last academic year, the number of teachers there increased by three percent. Thus, the Sondland Education Commission’s prediction of a teacher shortage as early as next academic year is unfounded.
Which of the following, if true, most seriously weakens the claim that the prediction of a teacher shortage as early as next academic year is unfounded?(C)
A. Funding for public elementary schools in Sondland is expected to increase over the next ten years.
B. Average salaries for Sondland’s teachers increased at the rate of inflation from last academic year to this academic year.
C. A new law has mandated that there be 10 percent more teachers per pupil in Sondland’s public schools next academic year than there were this academic year.
D. In the past, increases in enrollments in public elementary and secondary schools in Sondland have generally been smaller than increases in the number of teachers.
E. Because of reductions in funding, the number of students enrolling in teacher-training programs in Sondland is expected to decline beginning in the next academic year.
Situation In Sondland’s public schools this academic year, the number of students is one percent higher and the number of teachers three percent higher than they were last academic year. For this reason, the Sondland Education Commission’s prediction of a teacher shortage as early as next academic year is questionable.
Reasoning What evidence would most weaken support for the claim that there will be no teacher shortage next academic year? A teacher shortage will arise next academic year if the number of teachers needed will exceed the number of teachers employed. This will happen if the number of teachers needed increases without a sufficient increase in the number employed, or if the number employed decreases without a sufficient decrease in the number needed. Evidence that either or both of these changes will occur next academic year is evidence that the predicted shortage will occur, so any such evidence will weaken support for the claim that the prediction is unfounded.
A Increased funding will likely allow more teachers to be hired but will not necessarily increase the need for teachers, so it does not support the prediction of a teacher shortage (and indeed it very slightly undermines the prediction). Also, the funding is expected to increase over ten years, not necessarily next year. Furthermore, we are not told who expects this increase or why. Their expectation may be unjustifiable.
B A salary increase at the rate of inflation is equivalent to no change in the salary’s actual value. The absence of a change in real salary in the past academic year does not by itself support any prediction of a change in the number of teachers needed or employed next academic year.
C Correct. The schools will need a lot more teachers next academic year to satisfy this mandate. It may be difficult for the schools to hire enough teachers in time. This provides at least some reason to predict that a teacher shortage will result.
D This means the number of students per teacher has been generally declining. It does not suggest that next academic year the number of teachers needed will increase, nor that the number employed will decrease.
E This does support the prediction that a shortage of trained teachers will arise eventually. But the declining number of students in teacher-training programs next academic year probably will not reduce the number of teachers available to teach during that same year.
The correct answer is C.
2.Art restorers who have been studying the factors that cause Renaissance oil paintings to deteriorate physically when subject to climatic changes have found that the oil paint used in these paintings actually adjusts to these changes well. The restorers therefore hypothesize that it is a layer of material called gesso, which is under the paint, that causes the deterioration.
Which of the following, if true, most strongly supports the restorers’ hypothesis?(A)
A. Renaissance oil paintings with a thin layer of gesso are less likely to show deterioration in response to climatic changes than those with a thicker layer.
B. Renaissance oil paintings are often painted on wooden panels, which swell when humidity increases and contract when it declines.
C. Oil paint expands and contracts readily in response to changes in temperature, but it absorbs little water and so is little affected by changes in humidity.
D. An especially hard and nonabsorbent type of gesso was the raw material for moldings on the frames of Renaissance oil paintings.
E. Gesso layers applied by Renaissance painters typically consisted of a coarse base layer onto which several increasingly fine-grained layers were applied.
Situation Renaissance paintings are subject to deterioration due to changes in climate, but their actual paint is not a factor in this deterioration. Instead, restorers hypothesize, it is gesso, the material under the paint, that causes problems for the paintings.
Reasoning What would most strongly support the hypothesis that gesso is causing the deterioration? An indication that gesso is affected by climatic changes would be most helpful in supporting the hypothesis. What could show that gesso is affected in this way? If the extent of a painting’s deterioration is directly related to the amount of gesso used under that painting, then the gesso clearly plays some part in that deterioration.
A Correct. This statement properly identifies a point supporting the hypothesis.
B This suggests that another factor—the wood of the panels—has a role in the paintings’ deterioration. Thus it weakens the hypothesis that gesso causes the deterioration.
C This merely reinforces given information, that the paint itself is not responsible for the paintings’ deterioration.
D Because this gives no information about any connection between this especially hard and nonabsorbent type of gesso and the type of gesso used under the paint in Renaissance paintings, the properties and usage of the former type of gesso are irrelevant to the question of whether gesso is responsible for the paintings’ deterioration.
E Because we are told nothing about whether this technique of gesso application increases or decreases the likelihood that gesso will be affected by climatic change, it does not support the restorers’ hypothesis.
The correct answer is A.
3.A newly discovered painting seems to be the work of one of two 17th-century artists, either the northern German Johannes Drechen or the Frenchman Louis Birelle, who sometimes painted in the same style as Drechen. Analysis of the carved picture frame, which has been identified as the painting’s original 17th-century frame, showed that it is made of wood found widely in northern Germany at the time, but rare in the part of France where Birelle lived. This shows that the painting is most likely the work of Drechen.
Which of the following is an assumption that the argument requires?(A)
A. The frame was made from wood local to the region where the picture was painted.
B. Drechen is unlikely to have ever visited the home region of Birelle in France.
C. Sometimes a painting so closely resembles others of its era that no expert is able to confidently decide who painted it.
D. The painter of the picture chose the frame for the picture.
E. The carving style of the picture frame is not typical of any specific region of Europe.
Situation A 17th-century painting has been discovered that was either by Johannes Drechen from northern Germany or by French artist Louis Birelle. The painting’s original picture frame is made of wood widely found in 17th-century northern Germany but rare in the French region where Birelle lived. So the painting was probably the work of Drechen.
Reasoning Which of the five statements is an assumption required by the argument? If the painting is correctly attributed to Drechen, then the wood that the frame was made from probably came from the region where Drechen lived and did his painting. The argument assumes that the specific wood used in the frame came from northern Germany rather than from some other place where that wood might have been found, and where (for all we know) Birelle might have visited.
A Correct. Without an assumption equivalent to this, the argument would fail.
B This is not a required assumption (unlike, for example, the following: Drechen did not give the picture frame to Birelle as a gift).
C This is a truism but is not required to make the argument’s conclusion well supported.
D This does not need to be assumed; Drechen could, for example, have simply asked a local frame-maker to make a frame for his picture.
E Neither the affirmation nor the denial of this statement is needed to underpin the argument.
The correct answer is A.
4.Archaeologists working in the Andes Mountains recently excavated a buried 4,000-year-old temple containing structures that align with a stone carving on a distant hill to indicate the direction of the rising sun at the summer solstice. Alignments in the temple were also found to point toward the position, at the summer solstice, of a constellation known in Andean culture as the Fox. Since the local mythology represents the fox as teaching people how to cultivate and irrigate plants, the ancient Andeans may have built the temple as a religious representation of the fox.
Which of the following is an assumption on which the argument is based?(A)
A. The constellation known as the Fox has the same position at the summer solstice as it did 4,000 years ago.
B. In the region around the temple, the summer solstice marks the time for planting.
C. The temple was protected from looters by dirt and debris built up over thousands of years.
D. Other structural alignments at the temple point to further constellations with agricultural significance.
E. The site containing the temple was occupied for a significant amount of time before abandonment.
Situation A recently excavated 4,000-year-old temple contains structures that point toward the positions at the summer solstice of both the rising sun and a constellation known in local culture as the Fox. Local mythology represents the fox as teaching people how to cultivate and irrigate plants.
Reasoning What must be true in order for the argument’s premises to suggest that the temple was built to religiously represent the fox? The argument’s premises are all observations about current conditions: the current alignment at the summer solstice of the temple relative to the sunrise and to the constellation known as the Fox, the current local name for a constellation, and current local mythology. To support the conclusion about the temple’s original purpose, the argument has to assume that all these conditions may still be essentially the same as they were 4,000 years ago when the temple was built.
A Correct. If the constellation’s position at the summer solstice relative to the temple is different from what it was 4,000 years ago, the temple must not have been aligned to point toward it when it was built. In that case, the argument’s justification for associating the temple with that constellation and with the fox is undermined.
B This does not have to be assumed for the argument to succeed, though if true, it might strengthen the argument by providing additional evidence associating the temple with the mythological fox as a teacher of agriculture. But the argument could be just as strong if the solstice were instead associated with agricultural activities other than planting.
C Even if the temple was not protected from looters, the conditions described in the argument’s premises may still be the same as they were 4,000 years ago.
D This is not assumed. Additional structural alignments pointing to different constellations associated with mythological beings other than the fox might weaken or even undermine the argument’s justification for associating the temple with the fox specifically.
E The argument makes no assumption regarding how long the temple was occupied, or even regarding whether the temple was ever occupied.
The correct answer is A.
5.Meat from chickens contaminated with salmonella bacteria can cause serious food poisoning. Capsaicin, the chemical that gives chili peppers their hot flavor, has antibacterial properties. Chickens do not have taste receptors for capsaicin and will readily eat feed laced with capsaicin. When chickens were fed such feed and then exposed to salmonella bacteria, relatively few of them became contaminated with salmonella.
In deciding whether the feed would be useful in raising salmonella-free chicken for retail sale, it would be most helpful to determine which of the following?(A)
A. Whether feeding capsaicin to chickens affects the taste of their meat
B. Whether eating capsaicin reduces the risk of salmonella poisoning for humans
C. Whether chicken is more prone to salmonella contamination than other kinds of meat
D. Whether appropriate cooking of chicken contaminated with salmonella can always prevent food poisoning
E. Whether capsaicin can be obtained only from chili peppers
Situation Chickens will readily eat feed laced with capsaicin, which appears to protect them from contamination with salmonella bacteria that can cause food poisoning.
Reasoning What information would help determine whether using the feed would be an effective strategy for raising salmonella-free chicken for retail sale? In order for the strategy to be effective, it must be economically feasible for farmers to raise chickens using the feed, and there must be enough consumer demand for chickens raised this way. So any information about factors likely to affect either the economic feasibility of raising the chickens or consumer demand for them could be helpful in determining how useful the feed would be.
A Correct. If chicken producers tried to market meat from capsaicin-fed chickens without knowing whether the taste is affected, they would risk alienating consumers. Of course, if they found that the taste is affected, they would then need to do further investigations to determine how consumers would likely respond to the difference. If consumers did not like the taste, this could negatively affect demand for the chickens. In that case, using the feed would not be an effective way to raise chickens for retail sale.
B There are two ways this might be considered relevant. First, it might be thought that because capsaicin reduces the risk of salmonella poisoning in humans, it will also do so in chickens; but we already have good evidence of that in the argument. Second, it might be thought that, if the capsaicin does not produce chickens that are totally salmonella free, then if any capsaicin remains in the chickens, it will help prevent any humans who consume the chicken from getting salmonella poisoning. But the relevant issue is whether the capsaicin will make the chickens salmonella free, not whether humans will be protected whether the chickens are salmonella free or not.
C The susceptibility of other types of meat to salmonella contamination would not affect the usefulness of the feed for preventing such contamination in chicken.
D Presumably many people do not cook contaminated chicken appropriately, so consumers could still benefit from salmonella-free chicken whether or not appropriate cooking methods could prevent food poisoning.
E Regardless of whether capsaicin can be obtained from other sources, chili peppers may be a perfectly viable source.
The correct answer is A.
6.Which of the following most logically completes the argument below?
When mercury-vapor streetlights are used in areas inhabited by insect-eating bats, the bats feed almost exclusively around the lights, because the lights attract flying insects. In Greenville, the mercury-vapor streetlights are about to be replaced with energy-saving sodium streetlights, which do not attract insects. This change is likely to result in a drop in the population of insect-eating bats in Greenville, since_________.(D)
A. the bats do not begin to hunt until after sundown
B. the bats are unlikely to feed on insects that do not fly
C. the highway department will be able to replace mercury-vapor streetlights with sodium streetlights within a relatively short time and without disrupting the continuity of lighting at the locations of the streetlights
D. in the absence of local concentrations of the flying insects on which bats feed, the bats expend much more energy on hunting for food, requiring much larger quantities of insects to sustain each bat
E. bats use echolocation to catch insects and therefore gain no advantage from the fact that insects flying in the vicinity of streetlights are visible at night
Situation In areas with mercury-vapor streetlights, any insect-eating bats feed almost exclusively around the lights, which attract flying insects. In Greenville, mercury-vapor streetlights will soon be replaced with sodium streetlights that do not attract insects.
Reasoning What evidence would suggest that the change in streetlights will reduce Greenville’s population of insect eating bats? Since the sodium streetlights will not attract flying insects, the bats will probably stop focusing their feeding around Greenville’s streetlights after the lights are changed. A statement providing evidence that this will make it harder for the bats to get enough food to sustain themselves would support the conclusion that the change is likely to reduce Greenville’s bat population and thus would logically complete the argument.
A Insect-eating bats existed long before streetlights did, so they can probably find insects away from streetlights even if they hunt only after sundown.
B Greenville will almost certainly still have flying insects for the bats to eat after the change, even if those insects no longer gather around the streetlights.
C If anything, such a smooth transition would be less likely to disturb the bats and therefore less likely to reduce their population.
D Correct. Since there will be no local concentrations of flying insects around Greenville streetlights after the change, the bats will most likely have more trouble getting enough to eat, and that their local population will therefore fall.
E The advantage that the bats gain from mercury-vapor streetlights comes from the high concentration of: insects. The fact that the bats get no additional advantage from the insects’ visibility tells us nothing about what affect the change to a different type of light might have.
The correct answer is D.
7.Rats injected with morphine exhibit decreased activity of the immune system, the bodily system that fights off infections. These same rats exhibited heightened blood levels of corticosteroids, chemicals secreted by the adrenal glands. Since corticosteroids can interfere with immune-system activity, scientists hypothesized that the way morphine reduces immune responses in rats is by stimulating the adrenal glands to secrete additional corticosteroids into the bloodstream.
Which of the following experiments would yield the most useful results for evaluating the scientists’ hypothesis?(D)
A. Injecting morphine into rats that already have heightened blood levels of corticosteroids and then observing their new blood levels of corticosteroids
B. Testing the level of immune-system activity of rats, removing their adrenal glands, and then testing the rats’ immune-system activity levels again
C. Injecting rats with corticosteroids and then observing how many of the rats contracted infections
D. Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats’ immune-system responses
E. Injecting rats with a drug that stimulates immune-system activity and then observing the level of corticosteroids in their bloodstreams
Situation Rats injected with morphine exhibit decreased immune-system activity and increased levels of corticosteroids, which are secreted by the adrenal glands and can interfere with immune-system activity.
Reasoning What further experiment would help determine whether morphine reduces immune responses in rats by stimulating the adrenal glands to release more corticosteroids? Contrary to the scientists’ hypothesis, the experimental results might have occurred because the morphine injections directly reduced immune-system activity. Or the injections might have blocked some mechanism that reduces corticosteroid levels in the blood, even if the morphine did not stimulate the adrenal glands to produce more corticosteroids. To evaluate whether the scientists’hypothesis is more plausible than these rival hypotheses, it would be helpful to know whether similar experimental results would occur after morphine injections even if adrenal gland activity did not change.
A Morphine could stimulate the adrenal glands of rats with normal corticosteroid levels to produce more corticosteroids, whether or not it does so in rats whose corticosteroid levels are already heightened.
B Such an experiment would not involve morphine and thus would not help to determine how morphine affects immune-system activity in rats.
C Whether or not rats contract infections may not reliably indicate their levels of immune-system activity.
D Correct. If the immune system responses decreased after the morphine injections in this experiment, the hypothesis that it was by stimulation of the adrenal glands that morphine reduced immune-system activity would be undermined. But if no decrease in immune-system responses occurred, the hypothesis would be confirmed.
E Even if the mechanism by which a drug other than morphine increases immune-system activity were discovered, this discovery would not necessarily reveal the mechanism by which morphine reduces immune-system activity.
The correct answer is D.
8.Curator: If our museum lends Venus to the Hart Institute for their show this spring, they will lend us their Rembrandt etchings for our print exhibition next fall. Having those etchings will increase attendance to the exhibition and hence increase revenue from our general admission fee.
Museum Administrator: But Venus is our biggest attraction. Moreover the Hart’s show will run for twice as long as our exhibition. So on balance the number of patrons may decrease.
The point of the administrator’s response to the curator is to question(C)
A. whether getting the Rembrandt etchings from the Hart Institute is likely to increase attendance at the print exhibition
B. whether the Hart Institute’s Rembrandt etchings will be appreciated by those patrons of the curator’s museum for whom the museum’s biggest attraction is Venus
C. whether the number of patrons attracted by the Hart Institute’s Rembrandt etchings will be larger than the number of patrons who do not come in the spring because Venus is on loan
D. whether, if Venus is lent, the museum’s revenue from general admission fees during the print exhibition will exceed its revenue from general admission fees during the Hart Institute’s exhibition
E. whether the Hart Institute or the curator’s museum will have the greater financial gain from the proposed exchange of artworks
Situation A curator and a museum administrator debate whether lending a particular artwork to the Hart Institute in exchange for a loan of some of the Hart Institute’s artworks would increase or decrease attendance and revenue at the museum.
Reasoning Which of the curator’s explicit or implicit claims is the museum administrator questioning? The administrator’s statements that Venus is the museum’s biggest attraction and that the Hart Institute’s show will run twice as long as the museum’s exhibition do not directly conflict with my statement or assumption made by the curator. However, the administrator’s conclusion is that on balance the number of patrons at the museum may decrease if the curator’s proposal is followed. This conclusion calls into question the curator’s claim that the proposal will increase revenue from the general admission fee, since that claim presupposes that on balance the proposal will increase the number of visitors to the museum. (The context suggests that the administrator is using the term patrons to mean visitors rather than donors.)
A The administrator does not dispute that the Rembrandt etchings would probably increase attendance at the print exhibition but rather suggests that this increase would be exceeded by the loss of visitors to the museum while the Hart Institute borrows Venus.
B Neither the curator nor the administrator comments on whether the patrons attracted to the Rembrandt etchings would be the same people attracted to Venus.
C Correct. The curator implicitly infers that the former number will be larger than the latter, whereas the administrator questions this by asserting that the latter number may be larger than the former.
D The administrator does not question whether the revenue during the print exhibition will exceed the revenue during the Hart Institute’s exhibition, but rather whether it will exceed the loss of revenue during the Hart Institute’s exhibition.
E Neither the curator nor the administrator comments on whether the museum would gain more or less from the exchange than the Hart Institute would.
The correct answer is C.
9.Which of the following most logically completes the passage?
Leaf beetles damage willow trees by stripping away their leaves, but a combination of parasites and predators generally keeps populations of these beetles in check. Researchers have found that severe air pollution results in reduced predator populations. The parasites, by contrast, are not adversely affected by pollution; nevertheless, the researchers’ discovery probably does explain why leaf beetles cause particularly severe damage to willows in areas with severe air pollution, since(D)
A. neither the predators nor the parasites of leaf beetles themselves attack willow trees
B. the parasites that attack leaf beetles actually tend to be more prevalent in areas with severe air pollution than they are elsewhere
C. the damage caused by leaf beetles is usually not enough to kill a willow tree outright
D. where air pollution is not especially severe, predators have much more impact on leaf-beetle populations than parasites do
E. willows often grow in areas where air pollution is especially severe
Situation Leaf beetles damage willow trees, but predators and parasites keep leaf beetle populations in check. Air pollution reduces populations of predators but not of parasites. Leaf beetles damage willows especially severely in areas with severe air pollution.
Reasoning What would support the conclusion that air pollution’s effects on the predator populations (but not on the parasite populations) explains why leaf beetles damage willows the most in areas with severe air pollution? The word since preceding the blank space at the end of the passage indicates that the space should be filled with a premise supporting the conclusion stated immediately before the since. To support this conclusion, it would help to have evidence that predators play a predominant role in keeping leaf beetle populations in check, and thus that the reduction of predator populations by air pollution could be sufficient to enable leaf beetle populations to grow and cause especially severe damage.
A The fact that neither the predators nor the parasites directly contribute to harming the trees offers no reason to conclude that a difference in how they are affected by pollution would contribute to the harm that the beetles cause to the trees.
B If the parasites are more prevalent in areas with severe air pollution, then they are more likely to keep leaf beetle populations in check in those areas, despite the reduced predator populations. Thus, the decline in predator populations would more likely be insufficient to explain why the leaf beetles cause more damage in those areas.
C This observation is irrelevant to whether the decline in predator populations explains why leaf beetles damage willow trees more severely in areas with severe air pollution.
D Correct. This indicates that predators play a predominant role in keeping leaf beetle populations in check, so, as explained above, it supports the argument’s conclusion.
E This is not clearly relevant to whether the decline in predator populations explains why leaf beetles damage willow trees more severely in areas with severe air pollution. The argument’s conclusion could just as easily be true regardless of whether willows grow in such polluted areas frequently or infrequently.
The correct answer is D.
10.On May first, in order to reduce the number of overdue books, a children’s library instituted a policy of forgiving fines and giving bookmarks to children returning all of their overdue books. On July first there were twice as many overdue books as there had been on May first, although a record number of books had been returned during the interim.
Which of the following, if true, most helps to explain the apparent inconsistency in the results of the library’s policy?(C)
A. The librarians did not keep accurate records of how many children took advantage of the grace period, and some of the children returning overdue books did not return all of their overdue books.
B. Although the grace period enticed some children to return all of their overdue books, it did not convince all of the children with overdue books to return all of their books.
C. The bookmarks became popular among the children, so in order to collect the bookmarks, many children borrowed many more books than they usually did and kept them past their due date.
D. The children were allowed to borrow a maximum of five books for a two-week period, and hence each child could keep a maximum of fifteen books beyond their due date within a two-month period.
E. Although the library forgave overdue fines during the grace period, the amount previously charged the children was minimal; hence, the forgiveness of the fines did not provide enough incentive for them to return their overdue books.
Situation After a library started forgiving fines and giving bookmarks to children who returned all their overdue books, the number of books returned greatly increased, but so did the number of overdue books.
Reasoning Why might the policy have simultaneously increased the number of overdue books and the number of books being returned? In order to increase both these numbers, the policy must have resulted in more books being checked out, kept past their due dates, and then returned. But why would the policy have promoted that behavior? One possibility is that it rewarded the behavior. The policy involved giving children bookmarks as rewards for returning overdue books, while removing the fines that penalized the children for doing so. If the children liked the bookmarks, they might have tried to get more of them by deliberately checking books out in order to keep them past their due dates before returning them to get the bookmarks.
A Failing to keep accurate records of the number of children would not clearly increase the number of books being returned. And the policy change did not apply to children who returned only some of their overdue books.
B This suggests that the policy had limited effects, but does not help to explain why it had apparently inconsistent effects.
C Correct. This explains how the policy gave the children a motive to check out and return more books while also allowing them to keep more of the books past the due dates.
D This restriction would have limited the number of overdue books and thus would not help to explain why that number increased.
E This suggests that the policy had little effect but does not help to explain why it had apparently inconsistent effects.
The correct answer is C.
11.A certain species of desert lizard digs tunnels in which to lay its eggs. The eggs must incubate inside the tunnel for several weeks before hatching, and they fail to hatch if they are disturbed at any time during this incubation period. Yet these lizards guard their tunnels for only a few days after laying their eggs.
Which of the following, if true, most helps explain why there is no need for lizards to guard their tunnels for more than a few days?(A)
A. The eggs are at risk of being disturbed only during the brief egg-laying season when many lizards are digging in a relatively small area.
B. The length of the incubation period varies somewhat from one tunnel to another.
C. Each female lizard lays from 15 to 20 eggs, only about 10 of which hatch even if the eggs are not disturbed at any time during the incubation period.
D. The temperature and humidity within the tunnels will not be suitable for the incubating eggs unless the tunnels are plugged with sand immediately after the eggs are laid.
E. The only way to disturb the eggs of this lizard species is by opening up one of the tunnels in which they are laid.
Situation Lizards of a certain species dig tunnels in which they lay their eggs. Although the eggs fail to hatch if disturbed during their several weeks of incubation, the lizards guard the tunnels for only a few days after laying the eggs.
Reasoning What would help to explain why the lizards have to guard their tunnels for only a few days? For the lizards to survive as a species, their behaviors must ensure that enough of their eggs hatch. Thus, they must successfully prevent enough of their eggs from being disturbed in the tunnels throughout the several weeks of incubation. If guarding the tunnels for only a few days accomplishes this, then some other factor must prevent the eggs from being disturbed during the remaining weeks. Evidence of any such factor would help to explain why the lizards do not have to guard the tunnels longer. For example, to protect the eggs without guarding them, the lizards might conceal the tunnel entrances after the first few days. Or animals likely to disturb the eggs might only be present for those first days, in which case there would be nothing for the lizards to guard against thereafter.
A Correct. This suggests that the only creatures likely to disturb the eggs are other lizards of the same species digging tunnels to lay their own eggs at around the same time. If so, each lizard can safely leave its eggs unguarded after a few days because all the other lizards will have finished digging.
B Even if the incubation period varies somewhat, the passage says it always lasts several weeks. So this does not explain why the lizards have to guard the tunnels for only a few days.
C If many eggs fail to hatch even when undisturbed, that is all the more reason for the lizards to protect the remaining eggs from disturbance throughout the incubation period so that at least some will hatch. So it does not explain why the lizards guard their tunnels only for a few days.
D Whether or not immediately plugging the tunnels with sand is enough to protect the eggs, this behavior does not explain why the lizards subsequently guard the tunnels for a few days and then leave for the rest of the incubation period.
E Even if it is impossible to disturb the eggs without opening the tunnels, that does not explain why the lizards guard the tunnels for a few days and then leave for the rest of the incubation period.
The correct answer is A.
12.Most banks that issue credit cards charge interest rates on credit card debt that are ten percentage points higher than the rates those banks charge for ordinary consumer loans. These banks’ representatives claim the difference is fully justified, since it simply covers the difference between the costs to these banks associated with credit card debt and these associated with consumer loans.
Which of the following, if true, most seriously calls into question the reasoning offered by the banks’ representatives?(C)
A. Some lenders that are not banks offer consumer loans at interest rates that are even higher than most banks charge on credit card debt.
B. Most car rental companies require that their customers provide signed credit card charge slips or security deposits.
C. Two to three percent of the selling price of every item bought with a given credit card goes to the bank that issued that credit card.
D. Most people need not use credit cards to buy everyday necessities, but could buy those necessities with cash or pay by check.
E. People who pay their credit card bills in full each month usually pay no interest on the amounts they charge.
Situation Banks that issue credit cards tend to charge interest rates on the associated debt that are ten percentage points higher than the rates associated with \
13.Often patients with ankle fractures that are stable, and thus do not require surgery, are given follow-up x-rays because their orthopedists are concerned about possibly having misjudged the stability of the fracture. When a number of follow-up x-rays were reviewed, however, all the fractures that had initially been judged stable were found to have healed correctly. Therefore, it is a waste of money to order follow-up x-rays of ankle fractures initially judged stable.
Which of the following, if true, most strengthens the argument?(C)
A. Doctors who are general practitioners rather than orthopedists are less likely than orthopedists to judge the stability of an ankle fracture correctly.
B. Many ankle injuries for which an initial x-ray is ordered are revealed by the x-ray not to involve any fracture of the ankle.
C. X-rays of patients of many different orthopedists working in several hospitals were reviewed.
D. The healing of ankle fractures that have been surgically repaired is always checked by means of a follow-up x-ray.
E. Orthopedists routinely order follow-up x-rays for fractures of bones other than ankle bones.
Situation Often patients with ankle fractures that their orthopedists have judged not to require surgery are given follow-up x-rays to check whether the fracture healed correctly. An examination of a sample of those x-rays found that the ankle had, in each case, healed properly.
Reasoning The question is which of the options, if true, would most strengthen the argument. The argument is based on data concerning follow-up x-rays, each of which revealed no problem with the orthopedist’s initial judgment that the ankle fracture was stable (and would heal without surgery). This invites the question whether the follow-up x-rays are really needed. The argument concludes that they are a waste of money. But was the x-ray data truly representative of orthopedists generally? After all, some orthopedists—perhaps more experienced, better-trained, or employed at a facility with better staff or facilities—may be much better than others at judging ankle fractures. If we add the information that the data for the conclusion comes from many orthopedists working at many different hospitals, we have greater assurance that the x-ray data is representative, and the argument will be made much stronger.
A Neither the study nor the conclusion that is drawn from it concerns general practitioners, so this point is irrelevant.
B Naturally many ankle injuries do not involve fractures—x-rays may sometimes be used to determine this— but the argument concerns only cases where there have been ankle fractures.
C Correct. This shows that the sample of x-ray data examined was probably sufficiently representative of cases of ankle fracture judged to be stable by orthopedists.
D The argument does not concern cases of ankle fracture that have been surgically repaired.
E The argument concerns only x-rays of ankles. From the information given here, we cannot infer that orthopedists are generally wasteful in routinely ordering follow-up x-rays.
The correct answer is C.
14.In setting environmental standards for industry and others to meet, it is inadvisable to require the best results that state-of-the-art technology can achieve. Current technology is able to detect and eliminate even extremely minute amounts of contaminants, but at a cost that is exorbitant relative to the improvement achieved. So it would be reasonable instead to set standards by taking into account all of the current and future risks involved.
The argument given concerning the reasonable way to set standards presupposes that(B)
A. industry currently meets the standards that have been set by environmental authorities
B. there are effective ways to take into account all of the relevant risks posed by allowing different levels of contaminants
C. the only contaminants worth measuring are generated by industry
D. it is not costly to prevent large amounts of contaminants from entering the environment
E. minute amounts of some contaminants can be poisonous
Situation State-of-the-art technology can detect and eliminate even tiny amounts of environmental contaminants, but at a cost that is exorbitant relative to its benefits.
Reasoning What must be true in order for the argument’s premises to support its conclusion? The, argument is that environmental standards requiring the best results that state-of-the-art technology can provide are unreasonably expensive relative to their benefits, so it would be reasonable instead to set environmental standards that take into account all present and future risks from contaminants. In order for the premise to support the conclusion, the environmental standards based on presrnt and future risks would have to be less expensive relative to their benefits than the best results environmental standards are. Furthermore, setting the current and future risks environmental standards cannot be reasonable unless it is feasible to assess present and future risks as those standards require.
A The argument does not say which standards, if any, environmental authorities have set. In any case, such standards could be reasonable or unreasonable regardless of whether industry currently meets them.
B Correct. If taking future risks into account were infeasible, then applying the current and future risks standards would also be infeasible. And setting those standards would be unreasonable if they could not feasibly be applied.
C According to the stimulus, the proposed current and future risks standards would apply to industry and others. So those standards could be reasonable even if the unspecified others also generated contaminants worth measuring, and even if the standards required measuring those contaminants.
D Even if it were costly to prevent large amounts of contaminants from entering the environment, the benefits of doing so to prevent present and future risks might outweigh the costs.
E The current and future risks standards could take into account any poisoning risks posed by minute and ants of contaminants.
The correct answer is B.
15.The chemical adenosine is released by brain cells when those cells are active. Adenosine then binds to more and more sites on cells in certain areas of the brain, as the total amount released gradually increases during wakefulness. During sleep, the number of sites to which adenosine is bound decreases. Some researchers have hypothesized that it is the cumulative binding of adenosine to a large number of sites that causes the onset of sleep.
Which of the following, if true, provides the most support for the researchers’ hypothesis?(B)
A. Even after long periods of sleep when adenosine is at its lowest concentration in the brain, the number of brain cells bound with adenosine remains very large.
B. Caffeine, which has the effect of making people remain wakeful, is known to interfere with the binding of adenosine to sites on brain cells.
C. Besides binding to sites in the brain, adenosine is known to be involved in biochemical reactions throughout the body.
D. Some areas of the brain that are relatively inactive nonetheless release some adenosine.
E. Stress resulting from a dangerous situation can preserve wakefulness even when brain levels of bound adenosine are high.
Situation Adenosine is released from brain cells that are active. The amount of adenosine released increases during wakefulness, and it binds to more and more sites on cells in certain brain locations. The number of sites to which it is bound decreases during sleep. Researchers have hypothesized that the cumulative binding of adenosine to many sites causes the onset of sleep.
Reasoning Which of the five pieces of information most strongly supports the hypothesis? If the hypothesis is correct, then some factor that impedes the binding of adenosine should be closely associated with wakefulness. Therefore, finding some such factor, and observing that it is accompanied by wakefulness when the factor operates, would tend to confirm the hypothesis.
A Without further, more specific information, this piece of information suffices neither to confirm nor to refute the hypothesis.
B Correct. A finding that caffeine, known to induce wakefulness, inhibits adenosine from binding to sites on brain cells helps confirm the hypothesis.
C This piece of information lacks a clear relevance to the hypothesized impact on sleep, and therefore does not help confirm the hypothesis.
D This information lacks a clear relevance to the hypothesized impact on sleep, and therefore does not help confirm the hypothesis.
E What this indicates is that stress may impede the hypothesized sleep-inducing effect of adenosine. It does not refute the hypothesis but does not confirm it either.
The correct answer is B.
16.A two-year study beginning in 1977 found that, among 85-year-old people, those whose immune systems were weakest were twice as likely to die within two years as others in the study. The cause of their deaths, however, was more often heart disease, against which the immune system does not protect, than cancer or infections, which are attacked by the immune system.
Which of the following, if true, would offer the best prospects for explaining deaths in which weakness of the immune system, though present, played no causal role?(C)
A. There were twice as many infections among those in the study with the weakest immune systems as among those with the strongest immune systems.
B. The majority of those in the study with the strongest immune systems died from infection or cancer by 1987.
C. Some of the drugs that had been used to treat the symptoms of heart disease had a side effect of weakening the immune system.
D. Most of those in the study who survived beyond the two-year period had recovered from a serious infection somet me prior to 1978.
E. Those in the study who survived into the 1980s had, in 1976, strengthened their immune systems through drug therapy.
Situation This question presents a puzzling scenario and asks us to find a possible fact that could make the situation less puzzling. The scenario involves a study that was conducted a few decades ago on a certain group of older adults. Those with the weakest immune systems were much more likely to die within two years than were the other individuals in the study. However, among the individuals with the weakest immune systems, death was more often by heart disease, from which the immune system does not protect, than from cancer or infections, for which a strong immur e system is protective.
Reasoning For the participants in the study with the weakest immune systems, what might best explain the deatr s that were not due to weakness of the immune system?’We might expect that the people with the weakest immune systems would be more likely to die from diseases that a strong immune system would protect them from than from other diseases. An explanation of the deaths that were not due to weakness of the immune system would explain why this is not the case.
A This point is irrelevant. The hypothesis that the participants in the study with the weakest immune systems had more infections than did the other participants does not explain why those participants died from conditions that were not infections.
B Our question involves identifying a possible explanation for the deaths of the participants in the study with the weakest immune systems. This option, about the deaths of those with strong immune systems, is thus irrelevant.
C Correct. This option suggests that those with heart disease—which would not have been due to weakness of the immune system—would have nevertheless had a weaker immune system due to the administration of certain drugs. Those with heart disease may for this reason have been among those with the weakest immune systems. If the individuals with weak immune systems due to treatment for heart disease formed a large-enough portion of the patients with the weakest immune systems, then we would have an explanation for why those with the weakest immune systems were more likely to die from heart disease than from infections or cancer.
D This option is not specific enough for us to use in the explanation we are looking for. For example, the \
17.Most scholars agree that King Alfred (A.D. 849-899) personally translated a number of Latin texts into Old English. One historian contends that Alfred also personally penned his own law code, arguing that the numerous differences between the language of the law code and Alfred’s translations of Latin texts are outweighed by the even more numerous similarities. Linguistic similarities, however, are what one expects in texts from the same language, the same time, and the same region. Apart from Alfred’s surviving translations and law code, there are only two other extant works from the same dialect and milieu, so it is risky to assume here that linguistic similarities point to common authorship.
The passage above proceeds by(B)
A. providing examples that underscore another argument’s conclusion
B. questioning the plausibility of an assumption on which another argument depends
C. showing that a principle if generally applied would have anomalous consequences
D. showing that the premises of another argument are mutually inconsistent
E. using argument by analogy to undermine a principle implicit in another argument
Situation A historian argues that King Alfred must have written his own law code, since there are more similarities than differences between the language in the law code and that in Alfred’s translations of Latin texts. Apart from Alfred’s translations and law code, there are only two other extant works in the same dialect and from the same milieu.
Reasoning How does the reasoning in the passage proceed? The first sentence presents a claim that is not disputed in the passage. The second sentence presents a historian’s argument. Implicitly citing the undisputed claim in the passage’s first sentence as evidence, the historian proposes an analogy between the law code and Alfred’s translations, arguing on the basis of this analogy that Alfred wrote the law code. The third sentence of the passage casts doubt on this analogy, pointing out that it could plausibly apply to texts that Alfred did not write. The fourth sentence suggests that too few extant texts are available as evidence to rule out the possibility raised in the third sentence. Thus, the third and fourth sentences are intended to undermine the historian’s argument.
A As explained above, the passage is intended to undermine the conclusion of the historian’s argument, not to underscore (emphasize) it.
B Correct. The passage’s third and fourth sentences question the plausibility of the historian’s assumption that no one but Alfred would have been likely to write a text whose language has more similarities to than differences from the language in Alfred’s translations.
C Although there might well be anomalous consequences from generalizing the assumption on which the historian’s argument relies, the passage does not mention or allude to any such consequences.
D The passage does not mention, or suggest the existence of, any inconsistencies among the premises of the historian’s argument.
E Although the historian argues by analogy, the passage does not itself argue by analogy; it does not suggest any specific counteranalogy to undermine the historian’s argument.
The correct answer is B.
18.Parland’s alligator population has been declining in recent years, primarily because of hunting. Alligators prey heavily on a species of freshwater fish that is highly valued as food by Parlanders, who had hoped that the decline in the alligator population would lead to an increase in the numbers of these fish available for human consumption. Yet the population of this fish species has also declined, even though the annual number caught for human consumption has not increased.
Which of the following, if true, most helps to explain the decline in the population of the fish species?(D)
A. The decline in the alligator population has meant that fishers can work in some parts of lakes and rivers that were formerly too dangerous.
B. Over the last few years, Parland’s commercial fishing enterprises have increased the number of fishing boats they use.
C. Many Parlanders who hunt alligators do so because of the high market price of alligator skins, not because of the threat alligators pose to the fish population.
D. During Parland’s dry season, holes dug by alligators remain filled with water long enough to provide a safe place for the eggs of this fish species to hatch.
E. In several neighboring countries through which Parland’s rivers also flow, alligators are at risk of extinction as a result of extensive hunting.
Situation The alligators in a certain region prey heavily on a certain species of fish that is prized for human consumption. However, although in recent years hunting has reduced the population of alligaters in the region, the population of the prized freshwater fish species has declined. The annual number caught for human consumption has not increased.
Reasoning What might explain the decline in the population of the prized fish species, despite both the decrease in population of another species that preys heavily on the prized fish and the lack of increase in fishing for the species for human consumption?’The population of the fish species declined, despite both the presence of a factor that we might be expected to produce an increase in the population of the species and the absence of a factor that we might ordinarily expect to explain the decrease. This situation may seem puzzling, and we may thus wish to find an explanation for it.
A Given that fishers can work in parts of lakes and rivers that were formerly too dangerous to work in, we might expect fishing of the prized species to increase and thus expect the population of the species to decrease. Although this might explain a decrease in the population of the fish species if fishing for the species increased, we have been given reason to believe that fishing for the species decreased.
B As with option A, the statement in this option suggests that fishing in the region may have increased and thus that fishing for the prized fish species for human consumption may have increased. This might explain the decrease in the population of the fish species if the statement were correct. However, we have been given that fishing for the prized fish species for human consumption has decreased.
C The statement in this option provides an explanation of why the alligator hunting has occurred. Given that the alligators prey on the fish, this might help to explain an increase in the population of the prized fish species, had such an increase occurred. However, we are given that the population of the fish species in the region has decreased.
D Correct. Despite the fact that alligators prey on the prized fish species, this statement describes a way in which the fish species may be dependent on the alligators, in such a way that a decline in the population of the alligators could contribute to a decline in the fish species.
E The statement in this option serves to amplify a point that is given in the puzzling situation of a decline in the population of the fish species despite (among other factors) a decrease in the population of the alligators. It does not explain why a decline in the population of the alligator species may have contributed to a decline in the population of the fish species.
The correct answer is D.
19.A company plans to develop a prototype weeding machine that uses cutting blades with optical sensors and microprocessors that distinguish weeds from crop plants by differences in shade of color. The inventor of the machine claims that it will reduce labor costs by virtually eliminating the need for manual weeding.
Which of the following is a consideration in favor of the company’s implementing its plan to develop the prototype?(D)
A. There is a considerable degree of variation in shade of color between weeds of different species.
B. The shade of color of some plants tends to change appreciably over the course of their growing season.
C. When crops are weeded manually, overall size and leaf shape are taken into account in distinguishing crop plants from weeds.
D. Selection and genetic manipulation allow plants of virtually any species to be economically bred to have a distinctive shade of color without altering their other characteristics.
E. Farm laborers who are responsible for the manual weeding of crops carry out other agricultural duties at times in the growing season when extensive weeding is not necessary.
解析：Evaluation of a Plan
Situation A company plans to develop an automated weeding machine that would distinguish weeds from crop plants by differences in shade of color. It is supposed to reduce labor costs by eliminating the need for manual weeding.
Reasoning Which option describes a consideration that would favor the company’s plan? The passage supports the plan by claiming that the machine would reduce labor costs by virtually eliminating weeding by hand. The correct option will be one that adds to this support. Labor costs will be reduced only if the machine works well. The machine relies on shade of color to distinguish between weeds and crop plants. If crop plants can be bred to have distinctive color without sacrificing other qualities, it would be more likely that the machine could be used effectively.
A Greater variation among weed plants would make it more difficult for the machine to distinguish between weeds and crop plants, and this would make it less likely that the machine would be effective.
B This option tends to disfavor the effectiveness of the machine. The more changeable the colors of the plants to be distinguished, the more complex the task of distinguishing between weeds and crop plants based on their color.
C This option tends to disfavor the likely benefits of the machine because it indicates that manual weeding distinguishes weeds from crop plants by using criteria that the machine does not take into account. If the machine does not distinguish weeds from crop plants as accurately and reliably as manual weeding does, then the machine is less apt to make manual weeding unnecessary.
D Correct. Making crop plants easily distinguishable from weeds would facilitate the effective use of the weeding machine.
E This does not favor the company’s implementing the plan to develop the machine. There would still be tasks other than weeding that would require hiring staff. Thus there would still be labor costs even if the need for manual weeding were eliminated.
The correct answer is D.
20.Aroca City currently funds its public schools through taxes on property. In place of this system, the city plans to introduce a sales tax of 3 percent on all retail sales in the city. Critics protest that 3 percent of current retail sales falls short of the amount raised for schools by property taxes. The critics are correct on this point. Nevertheless implementing the plan will probably not reduce the money going to Aroca’s schools. Several large retailers have selected Aroca City as the site for huge new stores, and these are certain to draw large numbers of shoppers frorr neighboring municipalities, where sales are taxed at rates of 6 percent and more. In consequence, retail sales in Aroca City are bound to increase substantially.
In the argument given, the two portions in boldface play which of the following roles?(D)
A. The first presents a plan that the argument concludes is unlikely to achieve its goal; the second expresses that conclusion.
B. The first presents a plan that the argument concludes is unlikely to achieve its goal; the second presents evidence in support of that conclusion.
C. The first presents a plan that the argument contends is the best available; the second is a conclusion drawn by the argument to justify that contention.
D. The first presents a plan one of whose consequences is at issue in the argument; the second is the argument’s conclusion about that consequence.
E. The first presents a plan that the argument seeks to defend against a certain criticism; the second is that criticism.
Situation Aroca City plans to switch the source of its public school funding from property taxes to a new local sales tax.
Reasoning What argumentative roles do the two portions in boldface play in the passage? The first boldface portion simply describes the city’s plan. The next two sentences in the passage describe an observation some critics have made in objecting to the plan and say that the observation is correct. But then the second boldface portion rejects the critics’ implicit conclusion that the plan will reduce school funding. The final two sentences in the passage present reasons to accept the statement in the second boldface portion, so they are premises supporting it as a conclusion.
A The argument concludes that the plan is unlikely to reduce funding for the schools. The passage does not mention the plan’s goal, but presumably that goal is not to reduce school funding.
B The second boldface portion presents the argument’s conclusion, not evidence to support the conclusion. The passage does not mention the plan’s goal, but presumably that goal is not to reduce school funding.
C The passage does not say whether the plan is better than any other possible school funding plans.
D Correct. The plan’s likely effect on the amount of school funding is at issue in the argument, whose conclusion is that the plan probably will not reduce that funding.
E The second boldface portion does not criticize the plan, but rather rejects a criticism of the plan by stating that the plan will probably not reduce school funding.
The correct answer is D.
21.Which of the following most logically completes the argument?
A photograph of the night sky was taken with the camera shutter open for an extended period. The normal motion of stars across the sky caused the images of the stars in the photograph to appear as streaks. However, one bright spot was not streaked. Even if the spot were caused, as astronomers believe, by a celestial object, that object could still have been moving across the sky during the time the shutter was open, since_________.(D)
A. the spot was not the brightest object in the photograph
B. the photograph contains many streaks that astronomers can identify as caused by noncelestial objects
C. stars in the night sky do not appear to shift position relative to each other
D. the spot could have been caused by an object that emitted a flash that lasted for only a fraction of the time that the camera shutter was open
E. if the camera shutter had not been open for an extended period, it would have recorded substantially fewer celestial objects
Situation In a photograph of the night sky taken with the camera shutter open for an extended period, the images of stars appeared as streaks because of the stars’ normal motion across the sky, but one bright spot was not streaked.
Reasoning What would most strongly suggest that a celestial object moving across the sky could have caused the spot? An object moving across the sky that was bright throughout the time the camera shutter was open should have appeared as a streak in the photograph, just as the stars did. But if the moving object was bright for only a very brief moment, and thus not for an extended time while the camera shutter was open, the object’s movement may not have been captured in the photograph, and thus would appear in the photograph as an unstreaked bright spot.
A The argument is not about how bright the spot was compared to other objects in the photograph.
B Streaks caused by noncelestial objects such as satellites or airplanes do not explain how only one of many celestial objects moving across the sky could have produced the unstreaked spot.
C The passage indicates that the stars were shifting position relative to the camera, not relative to one another. In any case, this observation does not help to explain how a celestial object that may not have been a star but that was moving across the sky could have produced the unstreaked spot in the photograph.
D Correct. As explained above, a moving celestial object that only produced a momentary flash of light would produce an unstreaked bright spot in the photograph.
E This may be true, given that fewer celestial objects might have moved into the camera’s range of view if the camera shutter had not been open as long. But it does not provide any evidence that a moving celestial object could have produced the unstreaked spot.
The correct answer is D.
22.Economist: Paying extra for fair-trade coffee—coffee labeled with the Fairtrade logo—is intended to help poor farmers, because they receive a higher price for the fair-trade coffee they grow. But this practice may hurt more farmers in developing nations than it helps. By raising average prices for coffee, it encourages more coffee to be produced than consumers want to buy. This lowers prices for non-fair-trade coffee and thus lowers profits for non-fair-trade coffee farmers.
To evaluate the strength of the economist’s argument, it would be most helpful to know which of the following?(B)
A. Whether there is a way of alleviating the impact of the increased average prices for coffee on non-fair-trade coffee farmers’ profits
B. What proportion of coffee farmers in developing nations produce fair-trade coffee
C. Whether many coffee farmers in developing nations also derive income from other kinds of farming
D. Whether consumers should pay extra for fair-trade coffee if doing so lowers profits for non-fair-trade coffee farmers
E. How fair-trade coffee farmers in developing nations could be helped without lowering profits for non-fair-trade coffee farmers
Situation Poor farmers receive higher prices for fair-trade coffee. But paying extra for fair-trade coffee lowers prices for non-fair-trade coffee and thus lowers profits for non-fair-trade coffee farmers
Reasoning What would be most helpful to know to evaluate how well the economist’s observations support the conclusion that buying fair-trade coffee hurts more farmers in developing nations than it helps? The economist suggests that buying fair-trade coffee benefits farmers who grow it because they receive higher prices, but that it hurts non-fair-trade coffee farmers by reducing their profits. So to knew whether the practice hurts more farmers in developing nations than it helps, it would be helpful to know whether developing nations have more farmers who produce non-fair-trade coffee than produce fair-trade coffee.
A Even if there were some potential way of alleviating the negative impact from buying fair-trade coffee on non-fair-trade coffee farmers, it still could be that the practice hurts more developing-nation farmers than it helps. Alleviating the negative impact does not entail that there is no negative impact.
B Correct. If fewer than half of these farmers produce fair-trade coffee, then the economist’s observations do suggest that buying fair-trade coffee hurts more coffee farmers in developing nations than it helps. But if more than half do, those observations suggest the contrary.
C Although knowing this could be helpful in determining how intensely many farmers are economically affected by people buying fair-trade coffee, it is not helpful in determining whether more farmers are hurt than are helped.
D The argument’s conclusion is only about the economic impact of buying fair-trade coffee, not about how consumers should or should not respond to that impact.
E Knowing how the fair-trade coffee farmers could potentially be helped without hurting the other coffee farmers is irrelevant to assessing whether the practice of buying fair-trade coffee hurts more developing -nation farmers than it helps.
The correct answer is B.
23.Tanco, a leather manufacturer, uses large quantities of common salt to preserve animal hides. New environmental regulations have significantly increased the cost of disposing of salt water that results from this use, and, in consequence, Tanco is considering a plan to use potassium chloride in place of common salt. Research has shown that Tanco could reprocess the by-product of potassium chloride use to yield a crop fertilizer, leaving a relatively small volume of waste for disposal.
In determining the impact on company profits of using potassium chloride in place of common salt, it would be important for Tanco to research all of the following EXCEPT:(E)
A. What difference, if any, is there between the cost of the common salt needed to preserve a given quantity of animal hides and the cost of the potassium chloride needed to preserve the same quantity of hides?
B. To what extent is the equipment involved in preserving animal hides using common salt suitable for preserving animal hides using potassium chloride?
C. What environmental regulations, if any, constrain the disposal of the waste generated in reprocessing the by-product of potassium chloride?
D. How closely does leather that results when common salt is used to preserve hides resemble that which results when potassium chloride is used?
E. Are the chemical properties that make potassium chloride an effective means for preserving animal hides the same as those that make common salt an effective means for doing so?
解析：Evaluation of a Plan
Situation New environmental regulations will increase the costs of disposing of the salt water that results from the use of large amounts of common salt in leather manufacturing. The manufacturer is considering switching from common salt to potassium chloride, because the by-product of the latter could be reprocessed to yield a crop fertilizer, with little waste left over to be disposed.
Reasoning In order to determine whether it would be profitable to switch from using common salt to using potassium chloride, which of the five questions does the manufacturer NOT need to answer? The chemical properties making potassium chloride an effective means of preserving animal hides might be quite different from those that make common salt effective, but there is no particular reason for thinking that this would impact the profitability of switching to potassium chloride. The relevant effects on the preserved hides might be the same even if the properties that brought about those effects were quite different. Thus, without more information than is provided in the passage, this question is irrelevant.
A The savings in waste disposal costs that would be gained by switching to potassium chloride could be cancelled out if the cost of potassium chloride needed far exceeded that for common salt.
B If switching to potassium chloride would force the manufacturer to replace the equipment it uses for preserving hides, then it might be less profitable to switch.
C Even though there is said to be relatively little waste associated with using potassium chloride in the process, if the costs of this disposal are very high due to environmental regulations, it might be less profitable to switch.
D If the leather that results from the use of potassium chloride looks substantially different from that which results when common salt has been used, then the leather might be less attractive to consumers, which would adversely affect the economics of switching to potassium chloride.
E Correct. Note that the question as stated here presupposes that potassium chloride and salt are both effective means for preserving animal hides—so it does not raise any issue as to whether potassium chloride is adequately effective or as effective as salt (clearly, an issue of effectiveness would be relevant to profitability).
The correct answer is E.
24.Colorless diamonds can command high prices as gemstones. A type of less valuable diamonds can be treated to remove all color. Only sophisticated tests can distinguish such treated diamonds from naturally colorless ones. However, only 2 percent of diamonds mined are of the colored type that can be successfully treated, and many of those are of insufficient quality to make the treatment worthwhile. Surely, therefore, the vast majority of colorless diamonds sold by jewelers are naturally colorless.
A serious flaw in the reasoning of the argument is that(B)
A. comparisons between the price diamonds command as gemstones and their value for other uses are omitted
B. information about the rarity of treated diamonds is not combined with information about the rarity of naturally colorless, gemstone diamonds
C. the possibility that colored diamonds might be used as gemstones, even without having been treated, is ignored
D. the currently available method for making colorless diamonds from colored ones is treated as though it were the only possible method for doing so
E. the difficulty that a customer of a jeweler would have in distinguishing a naturally colorless diamond from a treated one is not taken into account
Situation Colored diamonds of a type that comprises 2 percent of all mined diamonds can be treated so that they are not easily distinguishable from more valuable, naturally colorless diamonds, but many are too low in quality for the treatment to be worthwhile.
Reasoning Why do the argument’s premises not justify the conclusion that the vast majority of colorless diamonds sold by jewelers are naturally colorless? Since the type of colored diamonds that can be treated make up only 2 percent of all mined diamonds, and many diamonds of that type are too low in quality for treatment to be worthwhile, the vast majority of mined diamonds must not be treated to have their color removed. However, we are not told what proportion of all mined diamonds are naturally colorless. Naturally colorless diamonds may be far rarer even than the uncommon diamonds that have been treated to have their color removed. Thus, for all we can tell from the passage, it could well be that most colorless diamonds sold by jewelers have been treated to remove all color.
A Even if some types of diamonds command higher prices for uses other than as gemstones, the types discussed in the passage evidently command high enough prices as gemstones to be sold as such by jewelers.
B Correct. The argument does not work if naturally colorless diamonds are rarer than treated diamonds, as they may be for all we can tell from the information provided.
C The argument’s conclusion is only that jewelers sell more naturally colorless diamonds than diamonds treated to be colorless. Whether jewelers sell any colored diamonds or other gemstones is irrelevant.
D The argument only concerns the types of colorless diamonds sold now, not the types that may be sold in the future if other treatment methods are discovered.
E The argument does suggest this difficulty but implies that even so there are too few treated diamonds available for jewelers to sell in place of naturally colorless ones.
The correct answer is B.