Summarize Argument
The author concludes that ginkgo did not directly enhance the mice’s memories. This is because ginkgo lowers stress levels, and memory is enhanced when very high stress levels are reduced.
Notable Assumptions
The author assumes that the mice in the experiment had very high stress levels. If this wasn’t the case, then the mice wouldn’t have benefited from the memory enhancement that stress reduction brings. The author also assumes that the two groups of mice who navigated the maze were in all respects equal. Some quirk in one of the groups could weaken the connection between ginkgo and memory.
A
The doses of ginkgo in the diet of the mice in the experiment were significantly higher than the doses that have been shown to reduce stress in mice.
If the doses were higher, then the mice surely would’ve gotten the stress-reducing benefits of ginkgo. In turn, this would’ve helped their recall.
B
Neither the mice who received the ginkgo nor the other mice in the experiment exhibited physiological signs of higher-than-normal stress.
Since none of the mice had higher-than-normal stress levels, the stress-relieving effects of ginkgo wouldn’t have improved recall. According to the author, those effects happen when stress levels are high.
C
Some chemical substances that reduce stress in mice also at least temporarily impair their memory.
Is ginkgo one of those substances? We don’t know.
D
Scientists have not yet determined which substances in ginkgo are responsible for reducing stress in mice.
We don’t care which substance in ginkgo is responsible for reducing stress. We simply care about the effects ginkgo has on mice.
E
The mice who received the ginkgo took just as long as the other mice to learn to navigate the maze.
We don’t care how long it took them to learn. We’re concerned with memory, so we care about how well they navigated the maze the second time.
"Surprising" Phenomenon
Why did Styron hammers outsell Maxlast hammers at the hardware store last week, even though both brands usually sell equally, and Maxlast hammers were on sale and displayed at the store entrance last week, while Styron hammers stayed at their regular spot and price?
Objective
The correct answer will be a hypothesis that explains a key difference in customers’ interest in the hammer brands before and after last week’s changes. It must either result in customers being more likely to buy Styron hammers, or less likely to buy Maxlast hammers.
A
For the first several seconds after shoppers enter a store, they do not take detailed notice of the store’s merchandise.
This explains the shift in customer interest in the hammer brands after last week's changes. Since customers don’t pay close attention in the first few seconds after entering a store, they were less likely to notice the Maxlast hammers displayed at the entrance.
B
Most of the hardware store’s customers are attracted by quality and service rather than low prices.
Just because customers prefer quality over low prices doesn’t mean they see lower-priced items as lower quality. Also, we don’t know which hammer brand is higher quality, or if they’re the same quality. So, we still can’t explain why Styron hammers outsold Maxlast last week.
C
Customers who bought the Maxlast hammers last week commonly mentioned the sale as their reason for buying a hammer at that time.
This makes the sale results even more surprising. If some customers bought Maxlast hammers because of the sale, why didn’t more customers do the same? We still don’t know why Styron hammers outsold Maxlast hammers during the week of the Maxlast sale.
D
The hardware store circulated flyers that publicized the sale prices on Maxlast hammers.
Again, this makes the sale results even more surprising. If the hardware store advertised the Maxlast sale, why did Styron hammers still outsell Maxlast hammers?
E
In general, a single item that is on sale will not motivate shoppers to make a special trip to a store.
Even if shoppers didn’t make a special trip to the hardware store to buy the discounted Maxlast hammers, it’s still surprising that Styron outsold Maxlast, especially because both brands usually sell equally.
Summary
The author concludes that the Asian elephant does not run. Why? Because the Asian elephant always has at least two feet on the ground at all times. In addition, it accelerates only by taking quick and longer steps.
Missing Connection
We’re trying to prove that the Asian elephant doesn’t run. But do we know from the premises what “running” requires? No. We don’t know what can establish that something doesn’t run. So, at a minimum, the correct answer should tell us what’s required to run.
To go further, we can anticipate some specific relationships that would make the argument valid. Any answer that gets us from one of the premises to “not run” could be correct. For example:
In order to run, something must have fewer than two feet on the ground at some point in time.
In order to run, something must accelerate in a way besides merely taking quicker and longer steps.
To go further, we can anticipate some specific relationships that would make the argument valid. Any answer that gets us from one of the premises to “not run” could be correct. For example:
In order to run, something must have fewer than two feet on the ground at some point in time.
In order to run, something must accelerate in a way besides merely taking quicker and longer steps.
A
If an animal cannot accelerate, then it cannot run.
But the Asian elephant can accelerate. So (A) doesn’t establish that the elephant can’t run.
B
To run, an animal must have all of its feet off the ground at once.
(B) establishes that running requires having all feet off the ground at once. But we know the Asian elephant doesn’t have all of its feet off the ground at once — it always has at least 2 feet on the ground. So (B) allows us to conclude that the Asian elephant doesn’t run.
C
The Asian elephant can walk as quickly as some animals run.
(C) doesn’t tell us what’s required to run. So it doesn’t establish that the Asian elephant can’t run.
D
It is unusual for a four-legged animal to keep three feet on the ground while walking.
(D) doesn’t tell us what’s required to run. So it doesn’t establish that the Asian elephant can’t run.
E
All four-legged animals walk with at least two feet on the ground at all times.
(E) doesn’t tell us what’s required to run. So it doesn’t establish that the Asian elephant can’t run.
Summarize Argument
The author concludes that the ban on fishing caused the fish population at Quapaw Lake to rebound. His evidence is that the fish population at Quapaw Lake rebounded after a fishing ban was put in place. On the other hand, the fish population at Highwater Lake, where there was no fishing ban, didn’t rebound.
Notable Assumptions
In order for the fishing ban to have made a difference at Quapaw Lake, the author must assume there was a substantial amount of fishing at Quapaw Lake before the ban went into effect. The author must also assume that no unaccounted-for outside factor (e.g. climate conditions, introduction of new species into the lake) caused the rebound.
A
Highwater Lake is in an area of the mountains that is highly susceptible to acid rain.
This provides an alternate explanation as to why the fish population at Highwater Lake continued to decline. However, for this to weaken the author’s conclusion we would need to know if Quapaw Lake isn’t located in an area highly susceptible to acid rain.
B
Prior to the ban, there was practically no fishing at Quapaw Lake.
The fishing ban couldn’t have caused the fish population to rebound at Quapaw Lake. There was hardly any fishing to begin with.
C
Highwater Lake is much larger than Quapaw Lake.
We don’t care how big the lakes are. We care about their fish populations and how fishing bans effect them.
D
Several other lakes in the Pawpaw mountains have recently had increases in their fish populations.
Perhaps those lakes also had fishing bans put in place.
E
There used to be a greater variety of fish species in Highwater Lake than in Quapaw Lake, but there no longer is.
We don’t care about variety. We care about the total population.
Ortiz: Are you sure? Do we know whether people living on busy streets have other lifestyle factors that are especially conducive to heart disease?
Summarize Argument: Phenomenon-Hypothesis
Merton points out that a study shows a correlation between living on very busy streets and heart disease. Merton hypothesizes that the higher heart disease rate of people on these streets is caused by air pollution from cars.
Ortiz responds that there might be other factors that are the cause of the higher heart disease rate among people who live on busy streets.
Ortiz responds that there might be other factors that are the cause of the higher heart disease rate among people who live on busy streets.
Describe Method of Reasoning
Ortiz responds by pointing out that there might be other explanations for the correlation observed in the study described by Merton. Merton’s explanation is that air pollution caused by cars is causing heart disease. Ortiz suggests that the real explanation might be related to other lifestyle factors.
A
raising a question about the validity of the study that Merton cites
Ortiz doesn’t question the validity of the study. He doesn’t question the truth of the correlation found in the study. What he questions is Merton’s explanation for that correlation. Merton’s explanation is not part of the study.
B
contending that Merton needs to take into account other effects of air pollution
Ortiz doesn’t point out the need to consider other effects of air pollution. He points out the need to consider other causes of heart disease.
C
claiming that Merton misunderstands a crucial aspect of the study’s findings
Ortiz doesn’t claim Merton misunderstands anything about the study’s findings. Ortiz might agree that Merton perfectly understands the results of the study. What Ortiz questions is Merton’s explanation of those results. Merton’s explanation isn’t part of the study’s findings.
D
raising a counterexample to the general conclusion that Merton draws
Ortiz doesn’t raise a counterexample. A counterexample would involve the existence of people who live on a busy street, but whose heart disease is not caused by air pollution. Ortiz doesn’t point out that this kind of person exists.
E
suggesting that alternative explanations for the study’s findings need to be ruled out
Ortiz, through rhetorical questions, suggests that the cause of heart disease for people on busy streets might be other lifestyle factors. To conclude that air pollution is the cause, we’d need to rule out these other explanations.