Logical reasoning PrepTest 115 · Section 2 · Question 7

Incorrect. The person need only be able to imagine sheep.

Incorrect. Even if the insomnia is a rare occurrence, the sheep-counting method could still be effective. Someone employing this method must not, thus, have chronic insomnia.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Must Be True

Stimulus Summary:
Problem - Sleep-preventing thoughts can come from either half of the brain, keeping someone awake
Solution - Count sheep
Why? - It occupies both halves of the brain, thus preventing sleep-preventing thoughts

Answer Anticipation:
This argument falls into a common pattern—it prevents a problem (being kept up by sleep-preventing thoughts) and proposes a solution (counting sheep). Interestingly, against this backdrop, we're being tasked with finding an answer that must be true—rare for an argument-based question!

When an argument serves as the basis for a Must Be True question, there's a new potential correct answer—the necessary assumption. Since we accept all the statements in the stimulus as true in this question type, anything that must hold for the argument to be valid and sound must be true—and that includes necessary assumptions.

So outside of understanding this argument and the details which themselves could serve as the basis for a correct answer, we also need to anticipate any necessary assumption. In problem/solution arguments, necessary assumptions usually take the form of statements establishing the proposed solution will, in fact, work—and that's backed up by the question stem specifically asking about this. Here, that would mean counting sheep can actually get someone to fall asleep. While we know that the activity fully occupies both sides of the brain, there's no indication that this, itself, doesn't prevent sleep! The argument instead assumes it does ("thereby excluding") in reaching an intermediate conclusion.

So let's stay open to two potential types of answers—ones that derive from details directly stated in the stimulus, and ones that bring up the necessary assumption.

Answer Explanation:
This answer reflects something that must be true for the solution to work, as this question stem asks us. Since the argument concludes counting sheep will allow someone with sleep-preventing thoughts to fall asleep, it must be the case that thinking of sheep itself doesn't prevent sleep.

Key Takeaway:
When a Must Be True question has an argument in the stimulus, a correct answer might raise a necessary assumption/premise for the conclusion to hold.

Incorrect. First, the solution presented is to imagine and count sheep—not just think about them. Second, the argument doesn't state that this causes the person to fall asleep—it instead eliminates sleep-preventing thoughts, which would pave the way for the person to be able to fall asleep if they were tired.

Incorrect. What happens in dreams is out of scope since this answer is about falling asleep.