LSAT Prep Test 86 - Critical Reasoning 1 - Answers + Explanations

1. Researcher: During the rainy season, bonobos (an ape species closely related to chimpanzees) frequently swallow whole the rough-surfaced leaves of the shrub Manniophyton fulvum. These leaves are likely ingested because of their medicinal properties, since ingestion of these leaves facilitates the elimination of gastrointestinal worms.

Which one of the following, if true, most strengthens the researcher’s argument?

2. Policy analyst: Those concerned with safeguarding public health by reducing the risk of traffic fatalities typically focus their efforts on automotive safety measures such as increasing seat belt use, reducing distracted driving, and improving automotive technology. But what would contribute the most to safeguarding public health is a reduction in total miles traveled on our roads. The fact is that traveling by car is itself a major risk factor.

Which one of the following most accurately expresses the overall conclusion drawn in the policy analyst’s argument?

3. Letter to the Editor: The arts section of this paper shows a lamentable bias toward movies and against local theatrical productions. Over the last year alone, the paper has published over five times as many movie reviews as Reviews of live plays.

Which one of the following, if true, most seriously weakens the argument?

4. Archaeologist: Our university museum possesses several ancient artifacts whose ownership is in dispute. Although the museum has documentation showing that the items were obtained legally, there is an overriding principle that any important ancient artifact belongs by rights to the nation on whose territory it was discovered. Given that an institution is obliged to honor those rights, our museum should return the artifacts.

Which one of the following most accurately expresses the overall conclusion of the archaeologist’s argument?

5. Many fictional works have characters who are supposedly is, able to accurately precognitive—that perceive future events. But a perception of a future event is accurate only if that event comes to pass. Thus, the plots of these works often show that the characters are not truly precognitive, since some of the future events the characters perceive do not in fact come to pass.

Which one of the following is an assumption on which the argument depends?

6. Economist: There have been large declines in employment around the globe, so it’s not surprising that the number of workers injured on the job has decreased. What is surprising, however, is that the percentage of workers injured on the job has also decreased.

Each of the following, if true, helps to explain the surprising result mentioned by the economist EXCEPT:

7. Monarch butterflies must contend with single-celled parasites that can cause deformities that interfere with their flight. In populations of monarch butterflies that have not migrated, as many as 95 percent are heavily infected by the parasites, while less than 15 percent of those in migrating populations are infected. This shows that migrating allows monarch butterflies to avoid these parasites.

The reasoning in the argument is flawed in that the argument overlooks the possibility that

8. When a bird flies, powerful forces converge on its shoulder joints. The bird’s wings must be kept stable during flight, which cannot happen unless something balances these forces. The only structure in birds capable of balancing them is a ligament that connects the wing to the shoulder joint. So that ligament must be .

Which one of the following most logically completes the argument?

9. As part of a project to enhance the downtown area, the transit authority plans to build a majestic new subway station on the Longview line. However, the cun-ent design of the station does not include a connection to the nearby Waterfront line.- Adding a tunnel from the station to the Waterfront line using the current design would make the station much more convenient to commuters but would also put the project over budget. Since the budget cannot be increased, a more modest station should be built so that a tunnel can be included.

Which one of the following principles, if valid, most helps to justify the reasoning in the argument above?

10. A study found that most of the strokes diagnosed by doctors occurred in the left side of patients’ brains. This suggests that right-side strokes are more likely than left-side strokes to go undiagnosed since .

The conclusion of the argument is strongly supported if which one of the following completes the passage?

11. When so many oysters died off the coast of Britain that some native species were threatened with extinction, the fact that the water temperature had recently risen was at first thought to be the cause. Later, however, the cause was determined to be the chemical tributyl tin (TBT), used to keep barnacles off the hulls of boats. Legislation that banned TBT has nearly eliminated that chemical from British waters, yet the populations of the endangered oyster species have not grown.

Which one of the following, if true, most helps to explain the failure of the native oyster populations to recover?

12. Pratt: Almost all cases of rabies in humans come from being bitten by a rabid animal, and bats do carry rabies. But there is little justification for health warnings that urge the removal of any bats residing in buildings where people work or live. Bats are shy animals that rarely bite, and the overwhelming majority of bats do not have rabies.

Which one of the following, if true, most weakens Pratt’s argument?

13. It has been said that understanding a person completely leads one to forgive that person entirely. If so, then it follows that complete self-forgiveness is beyond our reach, for complete self-understanding, however desirable, is unattainable.

A flaw in the reasoning in the argument above is that this argument

14. A popular complaint about abstract expressionist paintings—that “a child could paint that”—holds that their stylistic similarities to young children’s paintings show that they are no more aesthetically pleasing than those inexpert works. But most participants in a psychological study, when shown pairs of paintings consisting of an abstract expressionist painting and a preschooler’s painting, consistently rated the abstract expressionist painting as aesthetically better, refuting this complaint and thereby establishing that abstract expressionist paintings are aesthetically pleasing.

The argument depends on assuming which one of the following?

15. Xavier: The new fast-food place on 10th Street is out of business already. I’m not surprised. It had no indoor seating, and few people want to sit outside and breathe exhaust fumes while they eat. Miranda: The bank should have realized that with all the fast-food places on 10th Street, one lacking indoor seating was likely to fail. So it was irresponsible of them to lend the money for it.

It can be inferred from the dialogue that Xavier and Miranda agree that

16. In an island nature preserve, Common Eider nests are found in roughly equal numbers in highly concealing woody vegetation, wooden boxes, and open grasslands that do not conceal nests. Some Common Eiders lay their eggs in nests established by other Common Eiders, probably in order to locate them in an area that is maximally safe from predation. Although one would expect the nests concealed in woody vegetation to be most commonly selected by other females for laying their eggs, the female Common Eiders that lay their eggs in other birds’ nests most commonly select established nests in wooden boxes.

Which one of the following, if true, would most help to explain why, in this nature preserve, Common Eiders that lay their eggs in other birds’ nests most commonly select established nests in wooden boxes?

17. Researcher: In an experiment, 500 families were given a medical self-help book, and 500 similar families were not. Over the next year, the average number of visits to doctors dropped by 20 percent for the families who had been given the book but remained unchanged for the other families. Since improved family health leads to fewer visits to doctors, the experiment indicates that having a medical self-help book in the home improves family health.

The reasoning in the researcher’s argument is questionable in that

18. Farmer: Farming with artificial fertilizers, though more damaging to the environment than organic farming, allows more food to be grown on the same amount of land. If all farmers were to practice organic farming, they would be unable to produce enough food for Earth’s growing population. Hence, if enough food is to be produced, the currently popular practice of organic farming must not spread any further.

The reasoning in the farmer’s argument is most vulnerable to criticism on which one of the following grounds?

19. Although severing a motor nerve kills part of the nerve, it can regenerate, growing about 1 millimeter per day from the point of damage toward the muscle the nerve controlled. So, for example, a severed motor nerve that controlled a hand muscle requires a much longer time to regenerate if that nerve is severed at the shoulder rather than at the wrist. Furthermore, the growing cells require the original nerve sheath to guide them to the area that has lost function, but that sheath begins to disintegrate after about three months unless there is living nerve tissue within it.

The statements above, if true, most strongly support which one of the following?

20. Male boto dolphins often carry objects such as weeds or sticks. Researchers first thought this was play behavior, but it is more likely to be a mating display. If it were play rather than a mating display, we would expect females and juveniles to engage in the behavior, but only adult males do.

The pattern of reasoning in the argument above is most similar to that in which one of the following arguments?

21. Andy Warhol’s Brillo Boxes is a stack of boxes that are visually indistinguishable from the product packaging of an actual brand of scouring pads. Warhol’s Brillo Boxes is considered a work of art, while an identical stack of ordinary boxes would not be considered a work of art. Therefore, it is not true that appearance alone entirely determines whether or not something is considered a work of art.

The argument proceeds by

22. Stallworth claims that she supported the proposal to build a new community center. If Henning also supported that proposal, it would have received government approval. Since the proposal did not gain government approval, Henning must have failed to back it, despite his claims to the contrary.

Which one of the following arguments is most similar in its flawed reasoning to the argument above?