Logical reasoning PrepTest 134 · Section 2 · Question 15

Incorrect. First, this answer is too broad—remember that sampling flaw we were trying to avoid? By expanding from professional cyclists cycling to anyone engaged in sustained exercise, this answer can't be supported by the sample. Second, this answer talks about the psychological benefit being less—that doesn't account for Group C, which saw a decline in their psychological state.

Correct. Argument or Facts:
Facts

Question Type:
Must Be True

Stimulus Summary:
Study — Professional cyclists cycled at different intensities for an hour
Group A — 60% of recommended max heart rate
Group B — 70% of recommended max heart rate
Group C — 80% of recommended max heart rate
Results on depression and anger
A — Felt better
B — Felt about the same
C — Felt worse

Answer Anticipation:
We normally have studies brought up in flaw—based questions, and we start by looking at a sampling flaw and correlation/causation flaw. Here, however, we're tasked with drawing an inference from such a study, so we want to draw that inference without committing one of these flaws ourselves.

So to avoid the sampling flaw, we should be sure to pick an answer that can be supported by this sample—an answer about professional cyclists is safest. And to avoid the correlation/causation flaw, we should not pick an answer that's strong and definitive towards the causality here.

What we can pick is a weaker answer that connects heart rate and mood in some way. Something like, "For professional cyclists, the intensity of cycling can have an effect on mood."

Answer Explanation:
This answer limits itself to discussing the group from which the sample was drawn, and it draws a very weak connection between intensity and mood, which is supported by the stimulus. There, 3 groups each had a different effect on their mood and a different intensity to their workout. While this isn't enough to definitively prove a causal connection, it is enough to most strongly support such a weak one.

Key Takeaway:
The common errors in reasoning that we study to tackle flaw—based questions can still help you in Must Be True questions! In this question type, the flaws are related to the wrong answers—in general, answers are wrong because they commit one of these flaws. When you can start eliminating Must Be True answers based on the flaw they commit, or when you can anticipate wrong answers based on the features of the stimulus that can lead to faulty logic, you know you're an LSAT pro.

Incorrect. "Best" exercise is too strong of a statement here since only 3 intensities were studied. Maybe 50% had an even more beneficial effect on mood than 60%!

Incorrect. While the stimulus does support that exercise can affect depression, it doesn't support that the physical factors are as important in depression as the psychological ones. That comparison has no basis in the stimulus because the psychological factors aren't mentioned.

Incorrect. The stimulus discusses the psychological benefits of cycling, not the physical ones, so this answer is out of scope.