LSAT 144 – Section 4 – Question 13

LSAT 144 - Section 4 - Question 13

October 2015

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT144 S4 Q13
+LR
Flaw or descriptive weakening +Flaw
Math +Math
Part v. Whole +PvW
A
22%
162
B
4%
157
C
2%
159
D
71%
165
E
1%
151
134
150
166
 +Medium 147.675 +SubsectionMedium

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Government statistics show that the real (adjusted for inflation) average income for families has risen over the last five years. Therefore, since this year the Andersen family’s income is average for families, the family’s real income must have increased over the last five years.

Summarize Argument
The author concludes that the Andersen family’s real income must have increased over the last 5 years. This is based on the fact that the real average income for families has risen over the last five years, and this year the Andersen family’s income is average for families.

Identify and Describe Flaw
The author overlooks the possibility that the Andersen family’s income hasn’t changed in five years. Although they are at the average for family’s this year, that doesn’t mean they experienced an increase in income from previous years. They might have been above average in previous years, and the nation’s average income for families has simply caught up to their income.

A
ambiguously uses the term “average” in two different senses
“Average” in “average income for families” means the same thing as “average” in “income is average for families.” It refers to the figure taken by adding up the total income for all families and dividing the figure by the number of families.
B
fails to take into account inflation with respect to the Andersen family’s income
The argument concerns “real” income, which is defined as income that is “adjusted for inflation.” So the argument already takes into account inflation.
C
overlooks the possibility that most families’ incomes are below average
This possibility doesn’t undermine the argument, because the author never assumed that most families incomes are not below average. The argument is based on the average income for families. Reliance on that average doesn’t imply a belief about “most” families’ income.
D
fails to consider the possibility that the Andersen family’s real income was above average in the recent past
This shows why the Andersens’ income might not have increased. They are at the average for today, but that doesn’t imply they had a lower income in the past. They might have been above average in the past, and the average income has increased to their level.
E
presumes, without providing justification, that the government makes no errors in gathering accurate estimates of family income
The author doesn’t assume that the government never makes errors in gathering estimates for family income. Maybe, for example, the data for one family was reported incorrectly. That wouldn’t necessarily have significant impacts on the overall average income calculation.

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LSAT PrepTest 144 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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