Summary
For both C and S, if a prisoner tries to escape from their sector, C and S must leave their respective stations to pursue the prisoner.
If they are not pursuing an escaped prisoner, C and S cannot leave their stations until their replacements have arrived.
On May 11 at 9pm, C and S finished a four-hour shift and their replacements arrived at the end.
C had violated the rules described. S had not violated the rules described.
If they are not pursuing an escaped prisoner, C and S cannot leave their stations until their replacements have arrived.
On May 11 at 9pm, C and S finished a four-hour shift and their replacements arrived at the end.
C had violated the rules described. S had not violated the rules described.
Notable Valid Inferences
There’s no clear inference to draw, because there are many ways in which C could have violated the rules and S would not violate the rules. Let’s use process of elimination to identify what must be false.
A
Chelas and Stelma were at their respective stations at 9 P.M.
Could be true. C could have violated the rules by leaving his station and coming back before the end of the shift. Or C could have violated by failing to pursue a prisoner. S could have stayed at her station the whole time. Or she could have pursued an escaped prisoner.
B
Stelma left her station before 9 P.M. but Chelas did not.
Could be true. S could have left to pursue an escaped prisoner. And C could have violated by failing to pursue that escaped prisoner.
C
Chelas left his station before 9 P.M. but Stelma did not.
Could be true. C could have violated by leaving the station even though a prisoner wasn’t trying to escape. S could have followed the rules and stayed at her station.
D
A prisoner attempted to escape from Chelas and Stelma’s sector at 7 P.M. and neither Chelas nor Stelma left his or her station before 9 P.M.
Must be false. If a prisoner tried to escape from the sector at 7pm, S had to leave her station to pursue the prisoner, because we know she followed the rules.
E
A prisoner attempted to escape from Chelas and Stelma’s sector at 7 P.M. and both Chelas and Stelma left their stations before 9 P.M.
Could be true. S could have followed the rules by chasing the escaped prisoner. C could have violated the rules by leaving the station but for some other reason besides chasing the prisoner.
A
there are no potential sources for historical understanding other than written texts and the arts
The argument doesn’t assert or imply this. It simply argues that most of the surveyed historians neglect many important repositories of historical knowledge aside from written texts.
B
painting, architecture, music, dance, and culinary arts are important only as sources for historical understanding
The argument isn’t concerned with the worth of these sources outside of their historical value. It only discusses the value of these sources for historians.
C
there are no sources for historical understanding that are neither considered best by historians nor neglected by them
The argument takes this for granted. Though most of the surveyed historians don’t consider other sources than written texts to be the best for historical understanding, that doesn’t mean they neglect all other sources. They may utilize some sources they don’t consider best.
D
something other than written texts is the best source for historical understanding
The argument doesn’t take this for granted. It only states that the majority of the surveyed historians believe written texts to be the best source for historical understanding.
E
the other sources for historical understanding mentioned by the historians surveyed are not important repositories of historical knowledge
We don’t know that the argument assumes this. The argument doesn’t put forth a belief about the value of these sources. It only argues that the majority of the surveyed historians neglect these sources.
A
fails to define adequately the term “top management”
The author doesn’t need to define “top management.” A CEO is at the top of a company’s hierarchy.
B
presumes, without giving justification, that one is not indifferent to something that one considers a top priority
We don’t know if the author presumes this. The author only claims that CEOs don’t behave indifferently toward their employees’ needs and aspirations. He doesn’t address whether CEOs personally feel indifferent toward their employees’ needs and aspirations.
C
presumes, without giving justification, that the CEOs’ priorities tend to be misplaced
The author doesn’t discuss whether CEOs’ priorities tend to be misplaced. He just argues that the belief that CEOs behave indifferently toward their employees’ wants and needs is unfounded.
D
presumes, without giving justification, that the CEOs’ claims are reflected in actual practice
This is a key possibility that the author overlooks. Just because CEOs claim to highly value their employees’ wants and needs, that doesn’t necessarily mean that CEOs don’t act indifferently toward their employees’ wants and needs.
E
makes a generalization based on an unrepresentative sample
The sample that the author references, of 125 CEOs, is representative of top management. CEOs are at the top of their companies’ management hierarchy.
A
presumes, without providing justification, that nothing can have greater value than one’s own freedom
The author doesn’t presume this. She argues that one’s freedom is always worth the risk of losing one’s life, but she never says that nothing is more valuable than freedom. The author may believe that many things are more valuable than freedom.
B
fails to consider that it is not always possible to rebel physically against an encroachment on one’s freedom
The author doesn’t state or imply that she thinks it’s always possible to rebel physically against an encroachment on one’s freedom, and her stance on this issue is irrelevant to the soundness of her conclusion.
C
generalizes inappropriately from a single extreme case to a universal claim
This is the flaw that the author commits. Using a single, extreme example of someone locked in a cement room, the author then makes a universal claim that one’s freedom is always more valuable than the risk of losing one’s life. The example doesn’t necessarily justify the claim.
D
fails to establish that the freedom of others is worth taking risks for
The author’s argument isn’t concerned with the freedom of others. The author’s argument is only concerned with one’s own freedom and life.
E
overlooks the possibility that some people do not have the courage to take risks for freedom
We don’t know if the author overlooks this. However, even if she does, it has no bearing on whether her conclusion, that one’s freedom is always more valuable than the risk of losing one’s life, is valid.
A
John does not consider how others besides himself are affected by fluoridation of water.
John’s argument isn’t concerned with others besides himself. He only argues that he should stop drinking fluoridated water.
B
John does not consider whether fluoridated water causes other diseases.
John’s argument isn’t about other diseases. He only argues that he should stop drinking fluoridated water to avoid developing bone cancer.
C
John does not consider whether there were any brief periods during the 40 years in which fluoride was not added to the water.
Whether there were periods during the 40 years in which fluoride wasn’t added to the water is irrelevant. John argues he should stop drinking fluoridated water now.
D
John does not focus on the positive effects that fluoridated water has on people.
John’s argument isn’t concerned with positive effects of fluoridated water. He argues that he should stop drinking fluoridated water so he doesn’t develop bone cancer.
E
John does not consider the possibility of other causes of bone cancer.
John fails to consider this. John argues that ceasing to drink fluoridated water is the only way he can ensure that he won’t develop bone cancer, but he ignores the possibility that he could develop bone cancer for other reasons even if he stops drinking fluoridated water.
Summarize Argument
The advertisement claims that at least 50 million North Americans should take lactase supplements to help them digest dairy. How do we know? Well, in one study where participants drank a liter of milk on an empty stomach, a significant proportion had digestion troubles. By applying that proportion to the North American population, we get to 50 million.
Notable Assumptions
The advertisement assumes that drinking a liter of milk on an empty stomach accurately reflects people’s everyday dairy digestion needs. If people can generally handle smaller amounts of dairy just fine, then the study could be misleading.
The author also assumes that the sample group is equivalent to the general North American population—meaning that the participants weren’t unusually likely to be lactose intolerant.
The author also assumes that the sample group is equivalent to the general North American population—meaning that the participants weren’t unusually likely to be lactose intolerant.
A
Eating solid food when drinking milk can decrease the amount of lactase produced by the body.
This does not weaken the argument, We don’t know whether people normally drink milk while by itself or while eating food. If the former, then that makes no difference, because the participants weren’t eating. If the latter, then maybe even more people need lactase!
B
Most people who consume dairy products consume less lactose at each meal than the amount found in a liter of milk.
This weakens the argument by casting doubt on whether the study cited represents people’s normal dairy digestive needs. Maybe most people produce enough lactase for their usual dietary habits, even if a whole liter of milk at once would cause some problems.
C
The production of lactase by the human body increases with age.
This does not weaken the argument because we don’t know anything about the age of the study participants, nor how that corresponds to the general population. If the participants were younger than average, that might be a problem, but we have no idea.
D
Lactose intolerance can interfere with proper nutrition.
This does not weaken the argument, because it doesn’t tell us anything about how representative the study was of the general population. Sure, lactose intolerant people should take lactase—but we still don’t know if that means 50 million people.
E
Some dairy foods, such as cheese, contain a form of lactose more difficult to digest than that found in milk.
This does not weaken the argument, firstly because we don’t know what kind of dairy people usually consume, and secondly because if anything it indicates a greater need for lactase than the study does. Either way, this doesn’t undermine the “at least 50 million people” claim.
"Surprising" Phenomenon
Some patients wear glasses or contacts after receiving RK surgery, which is meant to make them unnecessary.
Objective
The correct answer must fail to explain why some RK patients need glasses or contacts after receiving surgery. Every wrong answer, meanwhile, will state a difference between the intentions of RK surgery and its actual effect on some patients that results in those patients wearing glasses or contacts afterward.
A
As the eye heals from an operation to correct nearsightedness, it may in fact overcorrect, causing the person to be farsighted.
This would make glasses or contacts necessary for some RK patients. An overcorrecting eye would necessitate glasses or contacts to correct the new problem caused by the surgery.
B
The more severe a patient’s nearsightedness, the less effective the corneal reshaping of RK will be in correcting the problem.
This implies that very nearsighted patients may not have their vision completely corrected by RK surgery, which would make eyeglasses or contacts necessary afterward.
C
Occasionally an RK patient’s eyes may heal differently, causing a difference in the two eyes’ visual acuity that can be overcome only with corrective lenses.
This would explain why some RK patients require glasses or contacts. If their eyes heal differently, the surgery will cause a new problem that glasses or contacts can fix.
D
RK patients who originally suffered from only mild nearsightedness may, if the cornea does not heal evenly, develop an astigmatism that requires corrective lenses.
This would explain why some RK patients require glasses or contacts. If they develop an astigmatism, glasses or contacts may be necessary to correct a new problem caused by the surgery.
E
Those who choose to undergo RK tend to be as nearsighted before this operation as those who choose not to undergo RK.
This does not explain why RK patients would need glasses or contacts after surgery. It refers only to patients before they receive the surgery, not the consequences of the surgery.
"Surprising" Phenomenon
Why were fewer bass caught after the power plant started discharging wastewater into the river?
Objective
The correct answer must fail to explain why fewer bass were caught downstream. Meanwhile, every wrong answer will state a difference between the periods before and after the power plant opened that implies bass were more scarce afterward, or that bass present were caught at a lower rate.
A
The discharged wastewater made the river more attractive to fish that are the natural predators of bass.
This would explain why fewer bass were caught after the power plant opened. Their predators became more prevalent, so the number of bass declined.
B
The discharged water was warmer than the normal river temperature, leading the bass to seek cooler water elsewhere.
This would explain why fewer bass were caught after the power plant opened. They fled for cooler water, decreasing their numbers in that part of the river.
C
Because of the new plant, access to the part of the river downstream from the plant was improved, leading to an increase in the number of anglers fishing for bass.
This does not explain the decrease because more anglers would cause more bass to be caught. This would contribute to an increase in the number of bass caught, not a decrease.
D
Because of the new plant, the level of noise downstream increased, making that section of the river a less popular place for anglers to fish.
This would explain why fewer bass were caught downstream. There may be no fewer bass, but the number of anglers fishing for them decreased, leading to fewer bass being caught overall.
E
The discharged wastewater created turbulence that disrupted the vegetation of the river downstream, destroying some of the bass’s natural habitat.
This would explain why fewer bass were caught downstream. Their habitat was destroyed, so bass perished or fled, leading to a decrease in their population.