Logical reasoning PrepTest 133 · Section 1 · Question 21

Incorrect. The premises here match up ("otherwise" is the same as saying "in all other scenarios"). However, the conclusion doesn't because it doesn't state that all classes are held in either a lab or normal classroom.

Incorrect. The premises here match up, but the conclusion doesn't. While it does have the same general form of, "If not A, then B," but it messes up those connections. The conclusion here should mention the necessary conditions of the rules—if not in a normal classroom, then in a lab.

Incorrect. This answer has parallel premises, but it's off in the conclusion. The stimulus concluded, "If not A, then B," whereas this answer states, "If A, then not B."

Incorrect. Yet another premise match! However, the conclusion starts off wrong in talking about a class with extensive lab work—to match the stimulus, it would have to talk about a necessary condition of the conditional premises, not a sufficient one.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Valid

Question Type:
Parallel Reasoning

Stimulus Summary:
Domestic long-distance call starting between 9am and 5pm → $.15/minute
Domestic long-distance call starting any other time → $.10/minute
Therefore - All domestic long-distance calls that don't cost $.10/minute cost $.15/minute

Answer Anticipation:
This argument establishes the cost of domestic long-distance calls started in a certain time period, and then it establishes the cost of the same domestic long-distance calls started at "any other" time cost $.15. Since the second statement is about "any other" time, that covers all possible domestic long-distance calls, and so the conclusion is valid in determining that all these calls cost either $.10 or $.15/minute.

The correct answer should similarly establish two rules that cover all situations, and then conclude that the outcomes for all possible situations fall into one of those two categories (alternatively, if it doesn't fall into one, it falls into the other).

Answer Explanation:
Like all the other answers, this answer has a premise match. Unlike all the other answers, this answer also has a conclusion match. It states that if one of the necessary conditions isn't present, the other is—just as the stimulus did. This is our answer.

Key Takeaway:
Each of these answers featured overall logic that sounded very similar to the stimulus. However, the elements in each wrong answer were slightly off in their placement in the conclusion.