Khan Academy Diagnostic Test

4.8. IMPORTANT: Numerous studies suggest that when scientific evidence is presented in a trial, jurors regard that evidence as more credible than they would if they had encountered the same evidence outside of the courtroom context. Legal theorists have hypothesized that this effect is primarily due to the fact that judges prescreen scientific evidence and allow only credible scientific evidence to be presented in the courtroom. Which one of the following would be most useful to know in order to evaluate the legal theorists' hypothesis? (A) whether jurors typically know that judges have appraised the scientific evidence presented at trial (B) whether jurors' reactions to scientific evidence presented at trial are influenced by other members of the jury (C) how jurors determine the credibility of an expert witness who is presenting scientific evidence in a trial (D) whether jurors typically draw upon their own scientific knowledge when weighing scientific evidence presented at trial (E) how jurors respond to situations in which different expert witnesses give conflicting assessments of scientific evidence

Correct: A (The strength of the hypothesis is influenced significantly by the answer to the question. If the answer to the question is "yes," the hypothesis is strengthened. If jurors know that judges have prescreened the scientific evidence presented in a trial, it makes sense to suggest that the screening processes is something that influences jurors' level of trust. If the answer to the question is "no," the hypothesis is weakened. If jurors are unaware that judges have prescreened the scientific evidence presented in a trial, it makes much less sense to suggest that the screening processes is something that influences jurors' level of trust—it's not even something they know about.) Wrong: C (Knowing this wouldn't help evaluate the hypothesis. The hypothesis and the effect it attempts to explain concern a difference between how much jurors trust scientific evidence presented in a trial and how they trust evidence presented outside the courtroom setting. How jurors distinguish between experts in trials is irrelevant.)

1.16. In most of this forest, the expected outbreak of tree-eating tussock moths should not be countered. After all, the moth is beneficial where suppression of forest fires, for example, has left the forest unnaturally crowded with immature trees, and __________. The conclusion of the argument is most strongly supported if which one of the following completes the passage? Choose 1 answer: (A) more than half of the forest is unnaturally crowded with immature trees (B) mature trees are usually the first to be eaten by tussock moths (C) usually a higher proportion of mature trees than of immature ones are destroyed in forest fires (D) the expected outbreak of tussock moths will almost certainly occur if no attempt is made to counter it (E) there are no completely effective countermeasures against the moth

Correct: A (This matches the prediction we made in the question overview, and it logically completes the argument. The argument is that we should allow moths to eat trees in this forest because moths are good for forests that are unnaturally crowded with immature trees. That reasoning is greatly strengthened if we know that this forest is one of the forests that are unnaturally crowded with immature trees.) Wrong: B (If anything, this claim has the opposite effect of what we're looking for. We can infer that we want the moths to eat the immature trees, since the forest is likely to be crowded with them. If the moths eat mature trees first, then we may not get the positive result we're looking for by not controlling the outbreak of moths.)

4.19. IMPORTANT: Jurist: To ensure that a legal system remains just, it is important to guarantee that lawbreaking does not give lawbreakers an unfair advantage over law abiders. Thus, notwithstanding any other goals that criminal punishment may serve, it should certainly attempt to ensure that criminal wrongdoing remains profitless. The jurist's claim that it is important to guarantee that lawbreaking does not give lawbreakers an unfair advantage over law abiders functions in the argument in which one of the following ways? (A) It states a condition that, if fulfilled, will ensure that a legal system remains just. (B) It expresses a principle that is offered as support for the conclusion. (C) It is a conclusion for which the only support offered is the claim that the legal system serves multiple goals. (D) It is a premise presented as support for the claim that the most important goal of criminal punishment is to ensure that criminal wrongdoing remains profitless. (E) It is presented as refuting an argument that criminal punishment has goals other than guaranteeing that lawbreaking remains profitless.

Correct: B (This accurately describes the role of the claim in question: There are really just two claims in the passage, one in each sentence, so our job is to determine which supports which. Here, the word "thus" clearly indicates that the first sentence (the core of which is the claim in question) supports the second sentence. The claim in question is general enough to be characterized as a principle.) Wrong: A (This distorts what's said in the passage. The author suggests that in order for a legal system to remain just, it's "important" to guarantee that lawbreaking doesn't give lawbreakers an unfair advantage. But that doesn't mean that meeting that condition ensures that a legal system will be just; there could be other elements that are also important for making a legal system just.)

4.16. Babblers, a bird species, live in large cooperative groups. Each member attempts to defend the group by sounding a loud bark-like call when it spots a predator, inciting the others to bark too. Babblers, however, are extremely well camouflaged and could usually feed safely, unnoticed by predators. These predators, indeed, generally become aware of the presence of babblers only because of their shrill barks, which continue long after most members of the group have been able to take cover and which signal the group's approximate location to the predators. Which one of the following, if true, would most help to explain the babblers' strange behavior? (A) Babblers fly much faster than the predators that prey upon them. (B) Babblers' predators are generally intimidated by large numbers of babblers. (C) There is more than one type of predator that preys upon babblers. (D) Babblers' predators have very good eyesight but relatively weak hearing. (E) Animals that live in close proximity to babblers are also preyed upon by the predators that prey upon babblers.

Correct: B (This suggests a way the barking might help protect babblers from predators and therefore helps explain the apparently strange behavior. We're told in the passage that when one babbler starts barking, the rest of the group joins in. If it's true that predators are intimidated by large numbers of babblers, then it's possible that the sound of many babblers barking together could scare them off. Thus, even though the barking might make predators aware of babblers' presence, it could ultimately help babblers more than it hurts them.) Wrong: D (This doesn't make the strange behavior seem any less strange. We're told in the passage that babblers are well enough camouflaged to feed safely without being noticed by their predators, so information that their predators have "very good" eyesight doesn't matter; we already know it usually isn't good enough to overcome babblers' camouflage. Similarly, we're told in the passage that babblers' barking is what generally makes their predators aware of their presence, so information that their predators have "relatively weak" hearing doesn't matter; we already know it's good enough to hear babblers' barking.)

4.23. IMPORTANT: Businessperson: Because the parking area directly in front of the building was closed for maintenance today, I was late to my meeting. If the maintenance had been done on a different day, I would have gotten to the meeting on time. After finding out that I could not park in that area it took me 15 minutes to find an available parking space, making me a few minutes late. The answer to which one of the following questions would be most useful to know in order to evaluate the reasoning in the businessperson's argument? (A) What were the reasons for performing maintenance on the parking area directly in front of the building on that-particular day? (B) Were any other of the meeting attendees also late to the meeting because they had difficulty finding parking? (C) What are the parking patterns in the building's vicinity on days when the parking area in front of the building is open? (D) Does the businessperson have a tendency to be late to meetings? (E) Was it particularly important that the businessperson not be late to this meeting?

Correct: C (Knowing the usual parking patterns around the building would help evaluate the argument; we'd be able to determine whether the extent of today's delays were something out of the ordinary. If on days when the parking lot is open there is always parking available in the parking lot and it always takes significantly less than 15 minutes to find a spot in the lot, then the argument would be strengthened. We'd have reason to believe that the extent of the delays experienced today was unusual and that the business person would have gotten to the meeting on time if the parking lot maintenance had been done on a different day. But if on days when the parking lot is open it often takes 15 minutes to find parking anyway (maybe the lot is normally full and street parking in the area is scarce), then the argument would be weakened. The business person quite possibly could have been late even if the maintenance hadn't been done today.) Wrong: D (This might seem to call into question the business person's conclusion (if the conclusion was just presented on its own), but it doesn't help us evaluate the given reasoning. That is, it doesn't affect whether the given conclusion follows from the given evidence. Regardless of the business person's tendencies, the delays the business person experience today, which coincided with parking lot maintenance, might (or might not) suggest that the business person would have been on time to today's meeting if there hadn't been maintenance today.)

4.20. VERY IMPORTANT: The company president says that significant procedural changes were made before either she or Yeung was told about them. But, according to Grimes, the contract requires that either the company president or any lawyer in the company's legal department be told about proposed procedural changes before they are made. Thus, unless what Grimes or the company president said is incorrect, the contract was violated. The argument's conclusion can be properly inferred if which one of the following is assumed? (A) Yeung is a lawyer in the company's legal department. (B) Neither Grimes nor Yeung was told about the procedural changes until after they were made. (C) No lawyer in the company's legal department was told about the procedural changes until after they were made. (D) If the company's president was told about the procedural changes before they were made, then the contract was not violated. (E) If no lawyer in the company's legal department was told about the procedural changes before they were made, then the contract was violated.

Correct: C (This allows the given conclusion to follow from the given support. The conclusion is that (as long as we take the cited statements to be accurate) the contract was violated. The contract, as cited, requires that the president or any of the lawyers in the legal department must be notified before changes are enacted. We learn in the stimulus that the president wasn't notified of a major change. Now, with the statement in this choice, we also know that none of the lawyers were notified. We can therefore conclude that, as long as we take the cited statement to be accurate, the contract was violated.) Wrong: A (This might make the information that Yeung wasn't told more relevant, but it doesn't allow the conclusion to be properly inferred from the support; we still don't know that the rule was violated. With this premise, we know that the president wasn't told and that one of the lawyers (Yeung) wasn't told. But that doesn't mean that none of the lawyers were told. There might be other lawyers in the legal department and one of them could could have been told, in which case the rule that either the president or any of the lawyers must be told before a change is enacted wouldn't have been violated.)

1.12. Sartore is a better movie reviewer than Kelly. A movie review should help readers determine whether or not they are apt to enjoy the movie, and a person who is likely to enjoy a particular movie is much more likely to realize this by reading a review by Sartore than a review by Kelly, even though Sartore is more likely to give a movie an unfavorable review than a favorable one. Which one of the following, if true, most strengthens the argument? (A) Sartore has technical knowledge of film, whereas Kelly is merely a fan. (B) Most of Kelly's movie reviews are unfavorable to the movie being reviewed. (C) One who is apt not to enjoy a particular movie is more likely to realize this by reading a review by Sartore than a review by Kelly. (D) Reading a movie review by Sartore will usually help one to enjoy the movie more than one otherwise would have. (E) Most of the movies that Sartore reviews are also reviewed by Kelly.

Correct: C (This information strengthens the argument. We're told that a person who would probably like a movie is much more likely to realize they'll like it by reading a Sartore review versus a Kelly review, and the principle by which the arguer evaluates a movie reviewer is whether that person's review helps readers determine whether or not they would like a movie. Because this choice tells us that a Sartore review would also alert someone to the likelihood that they won't like a movie (more so than a Kelly review would), it strengthens the positive comparison of Sartore's reviews to Kelly's reviews.) Wrong: D (This information neither strengthens nor weakens the argument. The goal of a good movie review is not to help a reader enjoy a movie more than they otherwise would have. Rather, the goal is to help a reader know whether or not they would enjoy the movie.)

1.8. Philosopher: It has been argued that because particular moral codes differ between cultures, morality must be entirely a product of culture and cannot be grounded in some universal human nature. This argument is flawed. Research suggests that certain moral attitudes, such as disapproval of unfairness and cruelty, are shared across all cultures. And just as certain universal tastes like sweetness and saltiness can, in different cultural contexts, provide the basis for many different cuisines, __________. Which one of the following most logically completes the argument? (A) moral codes tend to be based in the specific contexts in which they arise (B) the moral codes of most cultures resemble each other in many respects (C) a variety of moral codes can be based in shared moral attitudes (D) it is possible to understand the basis of the moral codes of different cultures (E) moral attitudes can be adapted to suit the moral codes of many different cultures

Correct: C (This matches the prediction we made in the question overview and logically completes the argument. The philosopher makes an analogy that some universal tastes can lead to different cuisines, and the blank represents the second part of the analogy. Given that the context of the argument is that the philosopher believes morality can be grounded in some universal human nature, we can infer that to complete the blank, we're looking for the idea that some universal moral beliefs can lead to different moral codes across cultures.) Wrong: D (This claim isn't relevant to the argument, so it doesn't logically complete the argument. What's possible to understand isn't addressed by the philosopher, so it can't act as logical support for a conclusion about moral codes being possibly grounded in universal morality.)

4.18. VERY IMPORTANT: For consumers, the most enjoyable emotional experience garnered from shopping is feeling lucky. Retailers use this fact to their advantage, but too often they resort to using advertised price cuts to promote their wares. Promotions of this sort might make bargain-minded consumers feel lucky, but they cut into profit margins and undermine customer loyalty. Which one of the following most accurately describes the overall conclusion drawn in the argument? (A) Feeling lucky is the most enjoyable emotional experience garnered from shopping. (B) Retailers take advantage of the fact that shoppers enjoy feeling lucky. (C) Advertised price cuts are overused as a means of gaining retail sales. (D) Using advertised price cuts to promote retail products reduces profit margins and undermines customer loyalty. (E) Making consumers feel lucky is usually not a good formula for retail success.

Correct: C (We know this is the overall conclusion because: It's stated in the passage. It's an idea-for-idea match for the claim made at the end of the second sentence—"too often they [retailers] resort to using advertised price cuts to promote their wares". It's supported by other statements in the passage. Why is it a bad idea to use advertised price cuts too much? Because "they [advertised price cuts] cut into profit margins and undermine customer loyalty." The statement itself isn't used to support anything else that's said in the passage. Nothing stated in the passage is implied to follow from the claim that advertised price cuts are used too much.) Wrong: D (This can't be the overall conclusion—it supports another claim in the passage. The author advances the claim that retailers too often resort to using advertised price cuts. The statement in this choice, which gives us some specific downsides of using advertised price cuts, provides grounds for believing that advertised price cuts are used more than they should be. Note that the reverse relationship doesn't make any sense at all; the claim that advertised price cuts are used more than they should be doesn't give any grounds for believing that advertised price cuts have specific downsides.)

4.25. At Morris University this semester, most of the sociology majors are taking Introduction to Social Psychology, but most of the psychology majors are not. Hence, there must be more sociology majors than psychology majors enrolled in the class. The flawed pattern of reasoning in the argument above is most similar to that in which one of the following? (A) Most of the paintings on display at the Metro Art Museum are from the twentieth century, but most of the paintings the Metro Art Museum owns are from the nineteenth century. It follows that the museum owns few if any of the twentieth-century paintings it displays. (B) In an opinion poll of Silver Falls residents, more said they were in favor of increased spending on roads than said they were in favor of increased spending on parks. So most Silver Falls residents must be in favor of spending more on roads but opposed to spending more on parks. (C) In the San Felipe city arboretum, most of the trees are of local rather than exotic species. Therefore, in the San Felipe area, there must be more trees of local species than of exotic species. (D) Most of the vegetables available at the Valley Food Co-op are organic, but most of the vegetables available at the Jumbo Supermarket are not. Thus, more organic vegetables are available at Valley Food than are available at Jumbo. (E) The Acme Realty website has photos of most of the houses, but of fewer than half of the condominiums, that Acme is offering for sale. So Acme must have more houses than condominiums for sale.

Correct: D (The pattern of reasoning in this choice matches the pattern of reasoning in the stimulus. In both, the support compares the proportions of two groups that have a particular trait, and the conclusion compares the numbers of group members that have the trait. Both arguments are flawed because they fail to consider that the total number of members in each group might be different (in the stimulus if there are many more psychology students total than sociology students, the argument would fall apart, and in this choice if there are many more vegetables at Jumbo Supermarket than at Valley Food Co-op, the argument would fall apart.) We can confirm that this is the answer by seeing that it can be put into the same abstract terms as the argument in the stimulus: Most X (vegetables available at the Valley Food Co-op) are Y (organic) Most Z (vegetables available at the Jumbo Supermarket) are not Y So more X than Z are Y.) Wrong: C (The pattern of reasoning in this choice isn't a good match for the pattern of the reasoning in the stimulus. For one thing, the support here doesn't match the support in the stimulus. In the stimulus we're given two supporting pieces of information: 1) most of the sociology majors at the school are taking Introduction to Social Psychology, but 2) most of the psychology majors at the school are not. Here, we are only given one supporting piece of information: 1) most of the trees in the arboretum are a local rather than exotic species. We could also eliminate this choice by noticing that it's flawed in a way that the stimulus isn't. Here, the author assumes without warrant that the trees at the arboretum are representative of the trees in the area. The argument in the stimulus doesn't assume some sample is representative of a whole.)

4.2. An unstable climate was probably a major cause of the fall of the Roman empire. Tree-ring analysis shows that Europe's climate underwent extreme fluctuations between 250 A.D. and 550 A.D., a period that encompasses Rome's decline and fall. This highly variable climate surely hurt food production, which made the empire harder to rule and defend. Which one of the following, if true, most strengthens the argument? (A) Political failures within the Roman empire during its last years led to conflicts that hampered agricultural production. (B) The areas of the Roman empire that had the greatest climatic instability between 250 A.D. and 550 A.D. did not experience unusual levels of unrest during that period. (C) Poor farming practices led to depleted soil in many parts of Europe during the last years of the Roman empire. (D) During periods when the Roman empire was thriving, Europe consistently experienced weather that was favorable for agriculture. (E) Total food production in Europe was likely greater in the years around 550 A.D. than in the years around 250 A.D.

Correct: D (This choice strengthens the argument by eliminating a potential weakness. If Rome's weather had always been bad for farming, the evidence that it was bad for farming during the decline wouldn't indicate that weather played a big role in Rome's decline. This choice tells us that Rome's weather wasn't always bad for farming—that the unfavorable weather that coincided with Rome's decline was something new, making it more likely that unfavorable weather was a major factor in causing Rome's decline.) Wrong: B (This comes closer to weakening the argument than to strengthening it. The argument advances the claim that climate instability was probably a major cause of the fall of the Roman empire. If it's true that the areas that had the greatest climatic instability weren't experiencing any more unrest than other places, then the supposedly major influence of climate instability is called somewhat into question.)

1.15. IMPORTANT: The production of leather and fur for clothing is labor intensive, which means that these materials have tended to be expensive. But as fashion has moved away from these materials, their prices have dropped, while prices of some materials that require less labor in their production and are more fashionable have risen. The situation described above conforms most closely to which one of the following generalizations? (A) The price of any manufactured good depends more on how fashionable that good is than on the materials it is made from. (B) It is more important for the materials used in the manufacture of clothing to be fashionable than it is for them to be practical. (C) Materials that require relatively little labor in their production tend to be fashionable. (D) The appearance of a manufactured good is the only thing that determines whether it is fashionable. (E) Cultural trends tend to be an important determinant of the prices of materials used in manufacturing.

Correct: E (The passage conforms to this principle. We're told that fashion trends have shifted away from leather and fur to other materials, and the prices of both types of clothing have adjusted in response to that shift.) Wrong: A (The situation in the passage doesn't illustrate the generalization in this choice. For one thing, the given situation concerns the price of materials (leather and fur) used in manufacturing, not the price of the actual manufactured goods. Furthermore, although in the given situation we have two factors that apparently affect price, we don't have one factor affecting price more than another factor.)