December 2004 LSAT Section 2 Question 10

The average cost of groceries will rise again next month. Consequently, butter and eggs can be expected to cost more ...

Jermaine1 on May 15, 2020

C and E

Hello, when choosing I was torn between C and E and went E on time. Would you be able to just explain the difference from why E would not be the correct answer.

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SamA on May 17, 2020

Hello @Jermaine1,

The author assumes that, because a group is trending in a particular direction, that each member of the group will follow the same trend. This is a pretty common error. The price of butter and eggs could remain the same, or even decrease. Each member of a group does not necessarily share the characteristics of the group as a whole. This is what we should be looking for among the answer choices.

Let's evaluate C. Fourth graders are just one part of the group "under 20." The group as a whole has recently started watching more TV. Can we assume that fourth graders alone reflect that trend? No, we cannot. This is the same "part-to-whole" error that appeared above.

Answer choice E is a valid argument. We are given a conditional statement: when the population of 20-30 year olds declines, real estate prices decrease.

20-30 Decline ---> Real Estate Prices Decrease

We are told that the population of that age group will decrease. Therefore, we can reasonably expect lower real estate prices. The conclusion follows logically from the premise. There is no "part-to-whole" relationship here.