Logical reasoning PrepTest 141 · Section 4 · Question 18

Incorrect. This argument isn't flawed—it's certainly possible that there are errors in the remaining pages. This answer is different from the stimulus where the prediction is about probability, not possibility—the former is much harder to prove than the latter, and the latter can be established by past trends (if it's happened before, it's at least possible it'll happen again).

Incorrect. This answer hops from a premise about there being "generally few errors" in a journal to there probably being "no errors"—that flip is different than the argument in the stimulus.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Flawed Parallel Reasoning

Stimulus Summary:
It usually rains in the valley in the summer, but it hasn't yet, so it probably will in the last summer week.

Answer Anticipation:
Basing a prediction about the future on a past trend? That's a common flaw on the LSAT. Whenever an argument says something will happen based on what has happened in the past, we've got our flaw. Let's find the answer choice that makes the same jump.

Answer Explanation:
This answer uses a past trend ("On average . . . ") to make a prediction about the future. Since there are generally a few errors in a journal, and none have yet been discovered, the argument concludes that there will probably be some discovered in the remaining pages. That's the same flaw from the stimulus and it matches the logical force, which is always a good sign that you're dealing with the correct answer.

Key Takeaway:
Timelines on the LSAT are almost always important when present! Here, the jump from the past to a prediction about the future was the key flaw that led to the correct answer. Always understand timelines and be sure to note when the LSAT is talking about the past, present, and future—especially the first and last of those!

Incorrect. Close! But not quite. While this answer does use past trends to make a prediction about the future, there are some key shifts. The answer is about Aisha proofreading several issues of a journal, not most of one issue with some outstanding pages (which would make it similar to the stimulus, where most of the summer has passed but there is still a week left). Since the conclusion here is based on there seldom being errors in issues of the journal, those other issues she reviewed don't support the conclusion (they're essentially irrelevant in this argument), and thus this argument is different from the stimulus.

Incorrect. This answer makes a determination about Aisha's proofreading, not the presence of errors in outstanding pages of the journal. It's also only about the past—Aisha's review and any mistakes she already made—when a key element of the flaw in the stimulus was the jump to a prediction about the future.