LSAT Explanation PT 23, S2, Q10: All bridges built from 1950 to

LSAT Question Stem

If the statements above are true, then, on the basis of those statements, which one of the following must also be true? 

Logical Reasoning Question Type

This is a Must Be True question. 

Correct Answer

The correct answer to this question is C. 

LSAT Question Complete Explanation

First, let's break down the passage:

1. All bridges built from 1950 to 1960 are in serious need of rehabilitation.

2. Some bridges constructed in this period were built according to faulty engineering design.

3. No suspension bridges are among the bridges that were built according to faulty engineering design.

Now, let's analyze the information in the passage. The passage states that all bridges built between 1950 and 1960 need rehabilitation, and some of these bridges have faulty engineering design. Additionally, it's important to note that no suspension bridges have faulty engineering design.

Think of this example: Imagine a box containing different types of fruits - apples, oranges, and bananas. If we say that all fruits in the box are ripe and some of them are apples, it means that at least one apple in the box is ripe.

The question type is a Must Be True (MBT) question, which means we need to find the answer choice that must be true based on the information provided in the passage.

Let's evaluate each answer choice:

a) Some suspension bridges are not in serious need of rehabilitation.

This answer choice is incorrect because the passage does not provide enough information about suspension bridges and their need for rehabilitation.

b) Some suspension bridges are in serious need of rehabilitation.

This answer choice is also incorrect because, again, the passage does not provide enough information about suspension bridges and their need for rehabilitation.

c) Some bridges that were built according to faulty engineering design are in serious need of rehabilitation.

This answer choice is correct because it aligns with the information given in the passage. Since all bridges built between 1950 and 1960 need rehabilitation and some of them have faulty engineering design, at least one bridge with a faulty design must need rehabilitation.

d) Some bridges built from 1950 to 1960 are not in serious need of rehabilitation.

This answer choice is incorrect because the passage clearly states that all bridges built between 1950 and 1960 need rehabilitation.

e) Some bridges that were built according to faulty engineering design are not bridges other than suspension bridges.

This answer choice is also incorrect because the passage states that no suspension bridges were built according to faulty engineering design.

The correct answer is C, as it is the only option that must be true based on the information provided in the passage.