Summary
Birds and mammals are infected with West Nile virus only through bites from mosquitoes. Mosquitos become infected when they bite infected birds or mammals. The virus was first detected in Africa and spread to North America. Humans can catch West Nile virus, but infected humans cannot infect a mosquito.
Strongly Supported Conclusions
Mosquitos infected with West Nile virus have been present in Africa and North America.
Humans are sometimes bitten by mosquitos infected with West Nile virus.
Humans are sometimes bitten by mosquitos infected with West Nile virus.
A
West Nile virus will never be a common disease among humans.
Unsupported. Humans can get the virus from mosquitoes, so they may be bitten by infected mosquitoes in large numbers in the future. There’s no evidence this won’t happen.
B
West Nile virus is most common in those parts of North America with the highest density of mosquitoes.
Unsupported. We know that humans can get West Nile virus, but we don’t know how common the virus is among mosquito populations in North America. Perhaps it’s most common in specific parts without dense mosquito populations.
C
Some people who become infected with West Nile virus never show symptoms of illness.
Unsupported. We don’t know anything about the symptoms of West Nile virus and whether people can have the virus without exhibiting symptoms.
D
West Nile virus infects more people in northern Africa than it does in North America.
Unsupported. We know that the virus was first detected in northern Africa. We don’t know whether that suggests the virus infects more people there than in North America. Maybe there are far fewer people to be infected there? Maybe the virus is more common North America?
E
West Nile virus was not carried to North America via an infected person.
Strongly supported. We know that infected humans cannot infect a mosquito. So, if the virus was found in North America, that means a mosquito must have bitten an infected bird or mammal. Either that mosquito or the infected bird or mammal carried the virus to North America.
"Surprising" Phenomenon
Why do people who have reduced their consumption of red meat eat, on average, a lot more fat than those who haven’t reduced their consumption of red meat?
Objective
The correct answer will tell us something that allows us to differentiate people who have reduced red meat consumption from those who haven’t, and this difference will lead to greater fat consumption among the people who reduced red meat consumption.
A
Many more people have reduced their consumption of red meat over the last two decades than have not.
The number of people who have reduced red meat consumption has no bearing on the average fat intake of those people. We’re talking about group averages here; the number of people in the group has no effect.
B
Higher prices over the last two decades have done as much to decrease the consumption of red meat as health concerns have.
The cause of reduced red meat consumption has no impact on the average fat intake of people who eat less red meat.
C
People who reduce their consumption of red meat tend to consume as much of other foods that are high in fat as do those who have not reduced their consumption of red meat.
This could be correct if it had said people who reduce red meat consumption eat more high-fat foods than others. But it just says they eat “as much” as others. That doesn’t explain why their average fat intake is higher than that of those who haven’t reduced red meat consumption.
D
People who reduce their consumption of red meat tend to replace it with cheese and baked goods, which are richer in fat than red meat.
This shows why people who reduce consumption of red meat, on average, end up eating more fat. They replace red meat with stuff that has more fat. People who don’t reduce red meat consumption have nothing to replace, so they don’t eat as much of the other higher-fat foods.
E
Studies have shown that red meat contains slightly less fat than previously thought.
We’d still expect people who reduce red meat consumption to reduce their fat intake, even if the expected reduction isn’t as great as we initially thought.
Tom: No, it isn’t. Its yard isn’t really as big as it looks. Property lines in Prairieview actually start 20 feet from the street. So what looks like part of the yard is really city property.
Rolanda: But that’s true of all the other properties we’ve looked at too!
Summarize Argument
Rolanda starts by concluding that the house on Oak Avenue is the best one to rent. This is because it has a larger yard than any other house they’ve looked at in Prairieview.
Tom concludes that the house on Oak Avenue isn’t the best one to rent. This is based on Tom’s belief that the yard of that house isn’t as big as it looks. Tom’s support for this belief is that property lines in Prairieview start 20 feet from the street; that means what looks like part of the house’s yard is actually part of the city’s property.
Rolanda responds by pointing out that every other property also has its property line start 20 feet from the street.
Identify and Describe Flaw
Tom’s flaw is that he doesn’t realize his point about the property line applies to every property. So he hasn’t shown that the Oak Avenue house isn’t the largest they’ve seen.
A
He fails to take into account the possibility that there are advantages to having a small yard.
Tom doesn’t make any comment about small yards; there’s no indication that his thoughts about small yards have anything to do with why his reasoning is flawed.
B
He presumes, without providing justification, that property that belongs to the city is available for private use.
Tom doesn’t make any claims concerning private use. There’s no indication he has any belief about whether property belonging to the city can be used privately.
C
He improperly applies a generalization to an instance that it was not intended to cover.
There’s no indication that the generalization (the rule about property lines) isn’t supposed to cover the house on Oak Avenue.
D
He fails to apply a general rule to all relevant instances.
Tom fails to apply the general rule (about property lines) to all relevant instances (other houses in Prairieview). Tom’s point is less persuasive because other houses would also have a smaller yard, making the Oak Avenue house still have a larger yard than other houses.
E
He presumes, without providing justification, that whatever is true of a part of a thing is also true of the whole.
Tom doesn’t argue that something true of a part is true of a whole. He applies a rule about measuring property lines to the house on Oak Avenue.
Summarize Argument
Jazz consists largely of voicelike horns and hornlike voices. Why the claim about “voicelike horns”? Because jazz horn players mimic the sound of voices by throwing in spontaneous twists and turns, giving their horn playing a voicelike quality. And why the claim about “hornlike voices”? Because the best jazz singers use their own voices in a similar way to how horn players use their horns. As an example of this, take the singer Billie Holiday, who thought of her singing voice as a horn.
Identify Argument Part
The claim referenced in the question stem is the first sentence in the stimulus. It’s a sub-conclusion that’s supported by the example of Billie Holiday, and goes on to support the second assertion made in the main conclusion: jazz consists, in part, of hornlike voices.
A
It is the argument’s main conclusion and is supported by another statement, which is itself supported by a further statement.
It’s not the main conclusion. It lends support to one half of the main conclusion: namely, that jazz consists, in part, of hornlike voices. Because it lends support, it cannot be the main conclusion.
B
It is the argument’s only conclusion, and each of the other statements in the argument is used to support it.
It’s not the argument’s conclusion. It lends support to one half of the conclusion: namely, that jazz consists, in part, of hornlike voices. Because it lends support, it cannot be the argument’s conclusion.
C
It is a statement for which some evidence is provided and which in turn is used to provide support for the argument’s main conclusion.
Accurately describes the statement’s role as a sub-conclusion. The example of Billie Holiday provides some evidence for the claim, and the claim then goes on to help support the main conclusion.
D
It is a statement for which no evidence is provided but which itself is used to support the argument’s only conclusion.
It’s supported by some evidence. The example of Billie Holiday lends support to the idea that the best jazz singers use their voices similarly to how horn players use their instruments.
E
It is a statement used to support a conclusion that in turn is used to support the argument’s main conclusion.
It does not support a sub-conclusion. Instead, it directly supports the main conclusion.
Summary
The author concludes that reducing class sizes in our district would probably not improve overall student achievement.
Why?
Because reducing class sizes requires hiring more teachers.
There’s already a shortage of qualified teachers in THIS REGION.
Education suffers when teachers are underqualified.
Why?
Because reducing class sizes requires hiring more teachers.
There’s already a shortage of qualified teachers in THIS REGION.
Education suffers when teachers are underqualified.
Notable Assumptions
We can’t attract enough qualified teachers from outside this region to work at our schools.
The benefit students would get from smaller classes does not outweigh the harm to education resulting from teachers who are underqualified.
The benefit students would get from smaller classes does not outweigh the harm to education resulting from teachers who are underqualified.
A
Class sizes in the school district should be reduced only if doing so would improve overall student achievement.
Not necessary, because the argument never argues that something should or should not be done. So it doesn’t need to assume anything about the circumstances necessary for when class sizes “should” be reduced.
B
At least some qualified teachers in the school district would be able to improve the overall achievement of students in their classes if class sizes were reduced.
Not necessary, because if it were not true — if NO qualified teachers would be able to improve overall achievement in their classes if class sizes were reduced — this doesn’t undermine the argument. In fact, it helps support the claim that reducing class sizes would not improve overall student achievement.
C
Students place a greater value on having qualified teachers than on having smaller classes.
What students value has no role in the reasoning of this argument. The argument concerns the effects of making class sizes smaller. We have no reason to think what students value more has any impact on the effects of reducing class sizes.
D
Hiring more teachers would not improve the achievement of any students in the school district if most or all of the teachers hired were underqualified.
Not necessary, because it’s too extreme. The author doesn’t need to assume that underqualified teachers would not improve the achievement of “any students in the school.” Even if they improve the achievement of some students, as long as they don’t improve the overall achievement of the school, the author’s reasoning still stands.
E
Qualified teachers could not be persuaded to relocate in significant numbers to the educator’s region to take teaching jobs.
Necessary, because if it were not true — if qualified teachers COULD be persuaded to relocate in significant number to the educator’s region to take teaching jobs — then the fact that there’s a shortage of qualified teachers in THIS REGION doesn’t necessarily establish that we’ll need to hire underqualified teachers to reduce class sizes. We might be able to hire qualified teachers who move in from other regions.
Summarize Argument: Causal Explanation
Global warming is unlikely to cause more frequent and intense tropical storms. Early predictions suggested that global warming would increase the frequency and intensity of tropical storms by raising ocean temperatures conducive to such storms. However, this is unlikely because global warming will have other effects, such as changes in wind flow, that will counteract its impact on tropical storm development.
Identify Conclusion
The conclusion is the geographer’s opinion that early predictions about global warming’s impact on tropical storm development were wrong. The geographer concludes that global warming will probably not cause more frequent and intense tropical storms.
A
Tropical storms are especially likely to form over warm ocean surfaces.
This answer is incorrect because it summarizes the context of the stimulus. It explains why some predicted that global warming would lead to more frequent and intense tropical storms: tropical storms are more likely to form over warm oceans.
B
Contrary to early discussions, global warming is not the only factor affecting the frequency and intensity of tropical storms.
This misstates the conclusion. The correct conclusion is that global warming will probably not result in more frequent and intense storms. However, this answer claims that the conclusion is about global warming not being the only factor affecting storm frequency and intensity.
C
If global warming were reversed, tropical storms would be less frequent and less intense.
This isn’t an argument made in the stimulus. The geographer doesn’t consider what would be required to reverse global warming; she only disputes one prediction about the effects global warming may have. Since this claim isn’t made in the stimulus, it can’t be the main conclusion.
D
Instabilities in wind flow will negate the effect of global warming on the formation of tropical storms.
This addresses a premise, not the main conclusion. The geographer uses global warming's effect on wind flow to support her conclusion that global warming won't lead to more intense and frequent storms. Since this claim is supporting evidence, it can't be the main conclusion.
E
Global warming probably will not produce more frequent and intense tropical storms.
This accurately captures the main conclusion: the geographer believes that predictions about global warming’s effect on tropical storms were likely incorrect. The answer summarizes this by stating that global warming probably won't lead to more frequent and intense storms.
Summarize Argument
The stimulus isn’t an argument yet, since there aren’t any premises. We are asked to support the conclusion by filling in the blank with a premise.
The author concludes that copyright sometimes goes beyond its original purpose, which was to promote the spread of ideas by allowing authors to earn fair financial rewards for their work. He supports this by saying that ______.
The author concludes that copyright sometimes goes beyond its original purpose, which was to promote the spread of ideas by allowing authors to earn fair financial rewards for their work. He supports this by saying that ______.
Notable Assumptions
To effectively fill in the blank, the correct answer must show how copyright sometimes goes beyond its original purpose of spreading ideas.
A
publication of copyrighted works is not the only way to circulate ideas
Irrelevant. There may be other ways to spread ideas, but spreading ideas was still the original purpose of copyright. (A) fails to address how copyright sometimes goes beyond that purpose.
B
authors are willing to circulate their works even without any financial reward
Irrelevant. Even if some authors circulate ideas without copyright, it doesn’t change the fact that the original purpose of copyright was to further circulate ideas. (B) fails to address how copyright sometimes goes beyond that purpose.
C
authors are unable to find a publisher for their copyrighted work
Irrelevant. The original purpose of copyright was to promote the spread of ideas by allowing authors to earn financial rewards for their work. The fact that some authors can’t find publishers tells us nothing about how copyright sometimes goes beyond that purpose.
D
there is no practical way to enforce copyrights
If copyrights are difficult to enforce, they may be unable to achieve their original purpose. But this doesn’t describe how copyrights sometimes go beyond their original purpose.
E
copyrights hold for many years after an author’s death
If an author is no longer alive, he can’t circulate ideas or earn financial rewards for his work. So, copyrights that hold after an author’s death are going beyond their original purpose.
Economist: There was nothing at all bumbling about my warning. Indeed, it convinced the country’s leaders to change economic policies, which is what prevented a recession.
Summarize Argument: Counter-Position
The economist concludes that his warning that the country’s economy would go into recession if policies weren’t changed was not bumbling. He supports this by saying that his warning led the country’s leaders to change economic policies, which prevented the recession.
Describe Method of Reasoning
The economist’s prediction relied on a condition. He predicted that the economy would go into recession if policies weren’t changed. But the economist shows that this condition wasn’t met— because of his warning, economic policies were changed. As a result, he concludes that his warning wasn’t bumbling and ineffective and suggests that it actually led to the prevention of the recession.
A
indicating that the state of affairs on which the economist’s prediction was conditioned did not obtain
The economist’s prediction was conditioned on economic policies staying the same. By showing that policies were changed (i.e. that “the state of affairs on which [his] prediction was conditioned did not obtain”), he refutes the critic’s claim that his prediction was bumbling.
B
distinguishing between a prediction that has not yet turned out to be correct and one that has turned out to be incorrect
The economist doesn’t suggest that his prediction might still be correct, nor does he distinguish between types of predictions. He’s not concerned with whether his prediction came to pass; instead, he focuses on disproving the claim that his warning was bumbling or pointless.
C
attempting to show that the critic’s statements are mutually inconsistent
The economist refutes the critic’s claim that his warning was bumbling, but he doesn’t point out any inconsistencies within the critic’s argument.
D
offering a particular counterexample to a general claim asserted by the critic
The critic asserts a very specific claim about the economist’s prediction, not a general one. And the economist doesn't respond by offering a counterexample, but shows that the condition on which his prediction depended was not met.
E
offering evidence against one of the critic’s factual premises
The economist implicitly accepts both of the critic’s factual claims (that he predicted a recession if policies weren’t changed and that economic growth was stronger this year). Instead of disputing these claims, he points out that the condition for his prediction wasn’t met.
Hospitals, universities, labor unions, and other institutions may well have public purposes and be quite successful at achieving them even though each of their individual staff members does what he or she does only for selfish reasons.
Summary
The individual staff members of hospitals, universities, labor unions, and other institutions do their work only for selfish reasons. However, the institutions themselves can still have public purposes and can achieve these public purposes successfully.
Strongly Supported Conclusions
Whether an institution can successfully achieve its public purpose may not depend on the intentions of that institution’s individual staff members.
An institution can possess a property that its members do not possess.
A
What is true of some social organizations is not necessarily true of all such organizations.
This is unsupported. The stimulus does not compare different kinds of social organizations; it only speaks to those institutions with public purposes.
B
An organization can have a property that not all of its members possess.
This is strongly supported. We are told that even though the staff members of an institution are selfishly motivated, the institution can have and achieve public purposes. Thus, the institution can have a property (pursuing public purposes) that not all of its members possess.
C
People often claim altruistic motives for actions that are in fact selfish.
This is unsupported. The stimulus does not tell us whether the staff members, who are selfish, claim to have altruistic motives. It merely tells us that the institution can have altruistic motives even though its members do not.
D
Many social institutions have social consequences unintended by those who founded them.
This is unsupported. The stimulus tells us nothing about the founders of these institutions or what their original intentions might have been. We only know that the institutions are currently able to have and achieve public purposes.
E
Often an instrument created for one purpose will be found to serve another purpose just as effectively.
This is unsupported. The stimulus does not refer to the creation or intended purpose of any instrument. We only know that an institution can have public purposes despite its selfish staff members.