LSAT Question Stem

The conclusion follows logically if which one of the following is assumed? 

Logical Reasoning Question Type

This is a Sufficient Assumption question. 

Correct Answer

The correct answer to this question is C. 

LSAT Question Complete Explanation

The question type for this problem is Sufficient Assumption, which means we need to find an assumption that, when added to the premise, guarantees the conclusion.

Let's first analyze the argument in the passage:

Premise: Maria won this year's local sailboat race by beating Sue, the winner in each of the four previous years.

Conclusion: We can conclude from this that Maria trained hard.

There is a gap in the argument since winning the race doesn't necessarily mean that Maria trained hard. To help bridge this gap, let's use the following labels:

A: Maria won

B: Maria trained hard

Now, let's evaluate the answer choices:

a) Sue did not train as hard as Maria trained.

This answer choice does not guarantee the conclusion that Maria trained hard. It only suggests that Maria trained harder than Sue, but it doesn't necessarily mean that Maria trained hard.

b) If Maria trained hard, she would win the sailboat race.

This answer choice is a Mistaken Reversal of the relationship needed to justify the conclusion. It states that if Maria trained hard, she would win, but it doesn't guarantee that Maria trained hard because she won.

c) Maria could beat a four-time winner only if she trained hard.

This is the correct answer choice. It matches the relationship we're looking for: A -> B (Maria won -> Maria trained hard). Adding this assumption to the premise guarantees the conclusion that Maria trained hard.

d) If Sue trained hard, she would win the sailboat race.

This answer choice doesn't help prove the conclusion. It only tells us that if Sue trained hard, she would win. Since we know Sue lost, it implies that Sue didn't train hard. However, this doesn't provide any information about whether Maria trained hard.

e) Sue is usually a faster sailboat racer than Maria.

This answer choice only addresses the relative speed of the two racers and does not help prove that Maria trained hard.

In summary, the correct answer choice is (c) because it provides the necessary assumption that guarantees the conclusion that Maria trained hard.