Logical reasoning PrepTest 118 · Section 1 · Question 7

Correct. Argument or Facts:
Facts

Question Type:
Must Be True

Stimulus Summary:
(1) Trust → Mutual respect
(2) Long-lasting relationship → Trust
(3) Personal relationship → Natural affinity
(4) Long-lasting personal relationship → Mutual respect AND Affinity

Answer Anticipation:
The argument has quite a few conditionals, and there's some overlap that can be used to form a chain:

Long-lasting relationship → Trust → Mutual Respect
not Mutual respect → not Trust → not Long-lasting relationship

Interestingly, that last conditional is an inference that can be made from earlier conditionals (combine all three to see how you could end up in that statement). With that chain made and the conditionals diagrammed out, let's head to the answer to see if we need to do more work.

Answer Explanation:
This answer talks about a personal relationship that won't be long-lasting. Based on that last conditional, we know that mutual respect and affinity are both required for a long-lasting personal relationship. So if either of those are missing, then the personal relationship won't be long-lasting (not Mutual respect OR not Affinity → not Long-lasting personal relationship). Since this answer talks about a friendship based "solely" by trust and mutual respect, there isn't affinity, which is enough to guarantee the personal relationship won't be long-lasting. This answer validly applies the contrapositive of the fourth conditional, so it's correct.

Key Takeaway:
When there are several conditionals and some chain together while others don't, don't get too obsessed with trying to get everything to work together. Instead, chain together what you can and then head to the answer choices to see if there's more work to be done. Here, the correct answer was derived from a single conditional, so any work you had done past the initial chain we built in the Anticipation step would have been a waste of time.

Incorrect. This answer is the reversal of the conditional relating trust and mutual respect—trust presupposes mutual respect, not the other way around.

Incorrect. This answer is a reversal of the final conditional, so it's unsupported.

Incorrect. The argument never compares the length of personal and professional relationships, so this answer is out of scope.

Incorrect. That affinity is necessary for the personal relationship to endure, but it's not sufficient for it.