LSAT 151 – Section 2 – Question 15

LSAT 151 - Section 2 - Question 15

September 2018

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT151 S2 Q15
+LR
Flaw or descriptive weakening +Flaw
Conditional Reasoning +CondR
Quantifier +Quant
Math +Math
A
7%
154
B
3%
151
C
5%
155
D
29%
157
E
56%
164
151
159
166
 +Harder 147.144 +SubsectionMedium

All the apartments on 20th Avenue are in old houses. However, there are twice as many apartments on 20th Avenue as there are old houses. Therefore, most old houses on 20th Avenue contain more than one apartment.

Summarize Argument

The author concludes that most old houses on 20th Avenue contain more than one apartment. He supports this by saying that all the apartments are in old houses, and there are twice as many apartments as old houses.

Identify and Describe Flaw

The author concludes that most— i.e. more than half— of the old houses have more than one apartment, just because there are twice as many apartments as old houses. But let’s say there are 10 old houses and 20 apartments. What if one old house contains all 20 apartments? What if 4 old houses contain 5 apartments?

It’s not necessarily true that most of the old houses contain more than one apartment. In fact, it’s possible that most of the old houses don’t contain any apartments at all!

A
overlooks the possibility that some of the buildings on 20th Avenue are not old houses

The author doesn't overlook this possibility. He says that there are twice as many apartments as old houses and that all the apartments are in old houses. But there might still be other buildings that are not old houses.

B
draws a conclusion that simply restates one of the premises offered in support of the conclusion

This is the cookie-cutter flaw of circular reasoning, where the conclusion is simply a restatement of one of the premises. The author doesn’t make this mistake. His premises may not support his conclusion well, but they are distinct from his conclusion.

C
fails to consider the possibility that some buildings on 20th Avenue may offer types of rental accommodation other than apartments

The author doesn’t overlook this possibility. His argument is only about the old houses and apartments on 20th Ave. There might be some buildings that are hotels or rental houses, but this doesn’t affect his argument.

D
confuses a condition whose presence would be sufficient to ensure the truth of the argument’s conclusion with a condition whose presence is required in order for the conclusion to be true

This is the cookie-cutter flaw of confusing necessary and sufficient conditions. The author doesn’t make this mistake; he never presents a condition sufficient to ensure the truth of the conclusion in the first place.

E
fails to address the possibility that a significant number of old houses on 20th Avenue contain three or more apartments

If a significant number of old houses have 3 or more apartments, the author can't conclude that most houses have at least one. For example, if there are 10 old houses and 20 apartments, it's possible that just 4 houses have 5 apartments, meaning most houses have no apartments.

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LSAT PrepTest 151 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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