LSAT Explanation PT 28, S3, Q11: A rise in the percentage of

LSAT Question Stem

Which one of the following statements, if true, most weakens the argument? 

Logical Reasoning Question Type

This is a Weaken question. 

Correct Answer

The correct answer to this question is C. 

LSAT Question Complete Explanation

First, let's analyze the argument in the passage. The passage states that there is a correlation between the rise in the percentage of all 18-year-olds who were recruited by the armed services and the rise in the percentage of young people who dropped out of high school. The conclusion drawn from this correlation is that the republic's recruitment rates for 18-year-olds depend substantially on recruitment rates for high school dropouts. The structure of the argument is as follows:

1. There is a correlation between the rise in the percentage of 18-year-olds recruited by the armed services and the rise in the percentage of high school dropouts. (Premise)

2. Therefore, the republic's recruitment rates for 18-year-olds depend substantially on recruitment rates for high school dropouts. (Conclusion)

The question type is a Weaken question, which asks us to identify the statement that, if true, most weakens the argument.

Now let's evaluate each answer choice:

a) A larger number of 18-year-old high school graduates were recruited for the republic's armed services in 1986 than in 1980.

- This answer choice provides information about the number of high school graduates recruited, but it does not address the relationship between recruitment rates for 18-year-olds and high school dropouts. It doesn't undermine the conclusion or the relationship between the premises and the conclusion.

b) Many of the high-technology systems used by the republic's armed services can be operated only by individuals who have completed a high school education.

- This answer choice tells us that some positions in the armed services require a high school education, but it doesn't provide information about the percentages or proportions of high school graduates and dropouts being recruited. It doesn't directly weaken the conclusion.

c) Between 1980 and 1986 the percentage of high school graduates among 18-year-olds recruited in the republic rose sharply.

- This answer choice weakens the argument by providing an alternative explanation for the rise in recruitment rates. If the percentage of high school graduates among 18-year-olds recruited increased sharply, it suggests that the recruitment rates may not depend substantially on high school dropouts. This is the correct answer.

d) Personnel of the republic's armed services are strongly encouraged to finish their high school education.

- This answer choice provides information about the encouragement given to personnel but does not address the relationship between recruitment rates for 18-year-olds and high school dropouts. It doesn't undermine the conclusion or the relationship between the premises and the conclusion.

e) The proportion of recruits who had completed at least two years of college education was greater in 1986 than in 1980.

- This answer choice provides information about college education, which is not relevant to the argument about high school graduates and dropouts. It doesn't undermine the conclusion or the relationship between the premises and the conclusion.

In conclusion, answer choice C is the correct answer as it provides an alternative explanation for the rise in recruitment rates, weakening the argument that the republic's recruitment rates for 18-year-olds depend substantially on recruitment rates for high school dropouts.