Logical reasoning PrepTest 124 · Section 2 · Question 10

Correct. Argument or Facts:
Facts

Question Type:
Cannot Be True

Stimulus Summary:
Fully concentrate → Above—average intelligence
Successfully trained in speed reading—most—Increased concentration

Answer Anticipation:
Cannot Be True questions that are based on conditional logic generally have a very specific correct answer—one that establishes the sufficient condition of a conditional, but states that the necessary condition isn't also present. This is impossible, because a conditional's sufficient condition being met guarantees the necessary condition.

Here, the stimulus has two statements—one a conditional, one a quantified statement.

First, it's important to note that these two statements can't be combined because they don't share a term. The closest it gets is in the discussion of concentration, but there's a gap between increased" concentration and the ability to "fully" concentrate.

As such, we need to treat these statements individually. And between the two of them, the first one is much more likely to lead to a correct answer. The reason for this is that a single example of someone who can fully concentrate but isn't of above—average intelligence would contradict it and thus be the correct answer. However, to contradict the most statement, there would need to be a much stronger answer.

Let's head in and expect the answer to break that conditional.

Answer Explanation:
While this answer tries to distract with information about speed—reading, the important part is that it triggers the sufficient condition of the conditional by talking about people who can fully concentrate. That guarantees these people are of above—average intelligence, but this answer states that they're not. Since this answer contradicts the conditional statement from the stimulus, it cannot be true and is thus correct.

Key Takeaway:
Cannot Be True questions that feature conditional logic will generally have correct answers that raise a sufficient condition before stating the necessary condition isn't present. Even when there are multiple statements, if one is conditional, the correct answer tends to follow this pattern and rely on contradicting just that conditional statement.

Incorrect. While learning to speed—read only usually" results in "increased" concentration, that doesn't preclude speed—readers from being able to fully concentrate, thus guaranteeing that they are of above—average intelligence. Additionally, there's nothing to say that there's not another sufficient condition to guarantee above—average intelligence—for example, it's possible that anyone who can speed—read is of above average intelligence! Since this answer doesn't contradict information from the stimulus, it could be true.

Incorrect. This answer reverses the conditional statement while weakening it and negating one of the terms. While that's not a valid inference, it being invalid doesn't guarantee that it's false, so it could be true. Remember—illegal reversals/negations are invalid/unsupported, but they could be true!

Incorrect. While speed—reading usually results in an increased ability to concentrate, that leaves open the possibility that it sometimes doesn't. Additionally, someone could increase their ability to concentrate while still having little ability to do so. Since this answer doesn't clash with the quantified statement, it's not the right answer.

Incorrect. This answer is too strong to be supported, but that doesn't mean that it cannot be true. It's possible that in the minority of cases where learning to speed—read doesn't result in increased concentration, it's because those people could already concentrate to some extent.