LSAT 101 – Section 3 – Question 19

LSAT 101 - Section 3 - Question 19

December 1997

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT101 S3 Q19
+LR
Sufficient assumption +SA
Conditional Reasoning +CondR
Link Assumption +LinkA
A
8%
164
B
2%
162
C
7%
165
D
83%
168
E
2%
158
132
146
160
 +Medium 146.901 +SubsectionMedium

J.Y.’s explanation

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Every student who walks to school goes home for lunch. It follows that some students who have part-time jobs do not walk to school.

Summary
The author concludes that some students with part-time jobs do not walk to school. His reasoning is that every student who walks to school goes home for lunch. Or, in contrapositive form, that all students who don’t go home for lunch don’t walk to school.

Missing Connection
The conclusion is about students with part-time jobs, but they aren’t mentioned in the premise. We need to bridge this gap to reach the conclusion that some students with part-time jobs do not walk to school.
By taking the contrapositive of the premise, we inferred that all students who don’t go home for lunch don’t walk to school. So, if at least some students with part-time jobs don’t go home for lunch, then some of them wouldn’t walk to school. This would guarantee the argument’s conclusion.

A
Some students who do not have part-time jobs go home for lunch.
This can’t be correct, because it tells us about some students who don’t have part-time jobs. Our conclusion is about students who do have part-time jobs. A “some” statement’s contrapositive isn’t automatically valid. So this tells us nothing about students with part-time jobs.
B
Every student who goes home for lunch has a part-time job.
This doesn’t help us reach our conclusion, because all it lets us infer is that some students with part-time jobs go home for lunch. We want to conclude that some students with part-time jobs do not walk to school.
C
Some students who do not have part-time jobs do not go home for lunch.
This can’t be correct, because it tells us about some students who don’t have part-time jobs. Our conclusion is about students who do have part-time jobs. A “some” statement’s contrapositive isn’t automatically valid. So this tells us nothing about students with part-time jobs.
D
Some students who do not go home for lunch have part-time jobs.
Every student who doesn’t go home for lunch doesn’t walk to school. So, if some students with part-time jobs don’t go home for lunch, some students with part-time jobs don’t walk to school. Note that “some” is bidirectional: saying some As are Bs is equivalent to saying that some Bs are As.
E
Every student who goes home for lunch walks to school.
This doesn’t mention students with part-time jobs, so it can’t be correct. We need an answer that bridges the gap between the premise and the conclusion.

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LSAT PrepTest 101 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Reading Comprehension

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