Logical reasoning PrepTest 149 · Section 3 · Question 21

Incorrect. It's possible that some subjects noted a pattern that tended to display the image at the top, and so they always went with the top to be more often accurate than not. As such, this answer is unsupported.

Incorrect. Don't start trying to think through the statistics here. You'd have to start analyzing the likelihood of getting a prediction correct when the image is mostly displayed at the top of the screen and . . . You can see that this is a rabbit hole, and one that the LSAT is almost certainly not going to have you go down. Additionally, there's a wide range for how frequently the image could appear at the top of the screen—from 51% of the time to 99% of the time—and the actual number would influence the analysis of this answer, making it very unlikely to be correct.

Incorrect. While the stimulus strongly suggests that there was no actual pattern, it doesn't suggest that people who perceived a pattern were being unreasonable in imagining one. It's possible that patterns were suggested by the semi-random display of images that only broke down with more instances of the image being displayed.

Correct. Argument or Facts:
Facts

Question Type:
Must Be True

Stimulus Summary:
Study Ð An image appeared usually at the top of a screen, sometimes at the bottom, and subjects were asked to predict where it would appear next
Outcome Ð They were wrong over 50% of the time, and would have been right over 50% if they had always guessed top
Subject reports Ð They based their guesses on patterns they thought they noticed

Answer Anticipation:
This question does a great job of highlighting why it's important to read a Must Be True question stem carefully. If this were a Must Be True question that asked us to find an answer that's "most strongly supported," then we'd anticipate an answer that generalizes (weakly) from this situation. This is because the stimulus establishes a general situation that doesn't really have much in the form of overlapping statements, conditionals, or other things that we'd normally use to derive an inference.

Something like, "People's behavior is sometimes influenced by patterns that don't exist." However, since it's asking for an answer that's 100% certain, so instead of looking for a generalization that's very strongly supported but can't be concluded with 100% accuracy, we should instead look for an answer that flows from the details in the passage.

As such, we shouldn't spend a lot of time anticipating, instead getting to the answer choices as soon as possible so we can analyze them against the stimulus.

Answer Explanation:
The subjects were wrong more often than they were right. That wouldn't have happened if they always guessed the image would appear at the top. And if they got lucky and were always right when they guessed the image was at the bottom, then they similarly would have been over 50% accurate. Therefore, some must have guessed the image would appear at the bottom incorrectly, and thus this answer is supported by the stimulus.

Key Takeaway:
When a Must Be True question has weaker language throughout the stimulus, look for weaker answers. Here, the stimulus was mostly made up of tendencies and broad statements, and the correct answer was about what "[s]ome" did.

Incorrect. Rationality is based on what can be known. Since the individuals didn't know that the image was set to appear at the top much more often than at the bottom, there's no reason to believe it was rational to always guess the image would appear at the top.