Self-study
Support In an experiment, some volunteers were assigned to take aerobics classes and others to take weight-training classes. █████ █████ ███████ ████ █████████ ██ ███████ ████████████ ████████████ ████ █████ ████ ██████████ ███ ██████████ ██████ ████████ ██ ███ ██████████ ██ ███ ████████ ███████ ████ ████ ████ █████ ██ ███ ██████████ ██ ███ ███████████████ ████████ ████ ████████ ████ ████████ ████ ███████ ████████ █████ ███ ████ ██████ █████████████ ███████
Summary
The author concludes that the experiment provides evidence that aerobic exercise helps the body handle psychological stress.
What makes the author think that?
Because in the experiment, some volunteers were assigned to aerobics classes and others were assigned to weight-training classes. After three months of these classes, each group performed a tough math calculation and had their measurable stress symptoms measured. The symptoms of the people who took aerobics classes were lower than the symptoms of those who took the weight-training classes.
Notable Assumptions
The author assumes that there isn’t some other difference between the two groups unrelated to the amount of aerobics exercise that explains the different results of the stress measurement.
The author assumes that the aerobics class group got more aerobics exercise overall than the weight-training group.
The author assumes that the aerobics class group did NOT do more weight-training overall than the weight-training group.
The author assumes that measurable stress symptoms following the performance of a tough math calculation are a reliable indication of the level of psychological stress.
21.
Which one of the following ██ ██ ██████████ ███ ████████ █████████
a
Three months is ██████ ████ ███ ███ ████ ██ █████ ███████ ████ ███████ █████████
Not necessary, because the author doesn’t have to assume that anyone “fully” benefited from aerobic exercise. Although the author does have to assume that three months is enough time to observe at least SOME of the benefits of aerobic exercise, this doesn’t require a belief about what length of time is required for FULL benefit.
b
The volunteers who ████ ████████ ██ ███ ████████ ███████ ███ ███ ████ ████ ███████ ███████ ███ ████████
Not necessary, because as long as the aerobics class group did not do MORE weight-training overall than the weight-training class group, they could still have done some weight-lifting.
c
On average, the ██████████ ███ ████ ████████ ██ ███ ████████ ███████ ███ ████ ████████ ██ ███ ██████ ██ █████ ████ ████ █████ ███████ ████ ████ ███ ████ ███████ ██████ █████████ ███ ███████████
Not necessary, because the author’s reasoning never relies on a comparison between the stress levels after three months to stress levels before the study started. The study wasn’t measuring an INCREASE or DECREASE in stress levels; it simply compared stress levels at 1 point in time between the aerobics class group and the weight-training class group.
d
On average, the ██████████ ████████ ██ ███ ████████ ███████ █████ ██ ████ █████████ ██ ███████ ███ ████████████ ███████████ ████ ███ ███ ██████████ ████████ ██ ███ ███████████████ ████████
Not necessary, because a comparison of difficulty is irrelevant. The point of the math calculation was to put people under some kind of stress-inducing activity so that we could measure the stress symptoms. Whether the calculation was more or less difficult for one group compared to the other doesn’t matter, because we can still measure someone’s stress after the calculation regardless of difficulty.
e
On average, the ██████████ ████████ ██ ███ ████████ ███████ ███ █ ███████ ██████ ██ ███████ ████████ ███████ ██████ ███ ███████████ █████████ ███ ████████ ███████ ███ ████████ ████ ███ ███ ██████████ ████████ ██ ███ ███████████████ ████████
Necessary, because the author must believe that a greater amount of aerobics exercise was the difference that explains the differing results on the stress measurements. If (E) were not true — if the aerobics class group actually got EQUAL or LESS aerobic exercise overall than the other group — then we have no reason to think aerobic exercise played a role in the differing stress levels.