Logical reasoning PrepTest 137 · Section 4 · Question 5

Correct. Argument or Facts:
Facts

Question Type:
Must Be True

Stimulus Summary:
Low humidity and heat (of lights) cause animal skins to deteriorate.Tungsten lamps give off more heat than compact fluorescent lamps but the same amount of light.

Answer Anticipation:
While this argument has a lot of framing, there are two key statements—a causal one, and a comparative one. These types of statements generally lead to correct answers in Must Be True questions, and these two overlap in content, so we should focus our efforts there.

The causal statements discuss two things that lead to animal skin deterioration in museum exhibits—low humidity and heat. The comparative statement establishes that tungsten lamps give off more heat than compact fluorescent lamps. So we can infer that exhibits lit with tungsten lamps are going to deteriorate more/faster than the ones lit by compact fluorescent lamps, other things being equal.

Answer Explanation:
All other things equal, a display lit by tungsten lamps—which emits more heat—will deteriorate faster than one lit by compact fluorescent lamps—which emit less heat. Since this answer is about replacing the lights on one display, other things will be equal, so this answer is supported.

Key Takeaway:
For Must Be True questions, answers generally come from comparisons, causality, conditionals, and strong statements. Especially when terms in any of these overlap with other statements in the stimulus.

Incorrect. The stimulus doesn't present enough information about the amount of heat emitted by each to allow this comparison to be drawn.

Incorrect. The stimulus doesn't establish what percentage of the displays are older and newer, so we can't draw this comparison.

Incorrect. Outside of establishing humidity as a source of deterioration, the stimulus doesn't discuss it again, so we have no way of knowing if it's a problem at this museum.

Incorrect. Similar to (D), there's not enough of a discussion of humidity to allow a conclusion to be drawn.