PrepTest 144
[lcid:3675] Prep Test 144 LSAT — Logical Reasoning — S4
Logical reasoning
Question prompt
Government statistics show that
Remaining source text redacted.
Why the credited answer is right
Credited answer: D
The notes below walk through why it fits the stem and how to eliminate the rest.
Question Type
Errors in Reasoning Questions
Answer choices
-
Aambiguously uses the term Remaining source text redacted.
Why choice A is not credited
Incorrect. There's no shift in the meaning of average here—it's not even clear what that second meaning would be. -
Bfails to take into Remaining source text redacted.
Why choice B is not credited
Incorrect. The stimulus's conclusion is about the Andersen families real income, and their income today is compared to the real income average, so it does take inflation into account. -
Coverlooks the possibility that Remaining source text redacted.
Why choice C is not credited
Incorrect. It doesn't overlook that possibility—it talks averages and then talks about a specific example, so the incomes of most families are already incorporated into that average. -
Dfails to consider the Remaining source text redacted.
Why choice D matches the stem
Correct. Argument or Facts:
Argument
Valid or Flawed:
Flawed
Question Type:
Errors in Reasoning
Stimulus Summary:
Avg. family income has increased over the past 5 years, and the Andersen family's income is average, so it must have gone up over the past 5 years.
Answer Anticipation:
This argument establishes a timeline and comparisons. The timeline is when a certain change happened, and the comparisons are between: 1) avg. family income from 5 years ago and today, and 2) the Andersen family's income today and the avg. family income today. The conclusion then compares the Andersen family's income today to that of 5 years ago.
However, there's one part of that timeline/comparison that's missing—the Andersen family's income from 5 years ago! The argument concludes that it went up, but there's no indication that their income was at the average from 5 years ago. It's possible their income was above the average 5 years ago and it hasn't changed, thus letting the average "catch up."
The correct answer, therefore, will have to address this lack of setting a baseline of the Andersen family's income from 5 years ago.
Answer Explanation:
This answer highlights that it never establishes a baseline against which to compare the Andersen family's income against where it used to be. If the Andersen family's real income was above average in the recent past, then the conclusion doesn't hold.
Key Takeaway:
Whenever the LSAT notes a timeline, pay attention. Whenever the LSAT makes a comparison, pay attention. When the LSAT creates a timeline to compare things over time, really pay attention! -
Epresumes, without providing justification, Remaining source text redacted.
Why choice E is not credited
Incorrect. If there's no reason to doubt the data, then it's not an assumption to rely on that data on the LSAT. Even then, the argument doesn't rely on there being no errors, just that the errors either aren't big enough to alter the conclusions or that they're random enough to cancel out.