PrepTest 138

[lcid:3650] Prep Test 138 LSAT — Logical Reasoning — S3 Logical reasoning

Question prompt

In the Riverview Building, Remaining source text redacted.
Why the credited answer is right

Credited answer: C

The notes below walk through why it fits the stem and how to eliminate the rest.

Question Type

Flawed Parallel Reasoning Questions

Answer choices

  1. A
    every fish has fur Remaining source text redacted.
    Why choice A is not credited
    Incorrect. Cat → Fur
    Cat → not Fish
    Therefore - Fish → Fur. So close, but that last term would need to be the negated version of the necessary condition of the first conditional to match the stimulus.
  2. B
    some cats lack fur Remaining source text redacted.
    Why choice B is not credited
    Incorrect. We can jump out as soon as we see that "some"—there's no equivalent quantifier in the stimulus.
  3. C
    no dog has fur Remaining source text redacted.
    Why choice C matches the stem
    Correct. Argument or Facts:
    Argument

    Valid or Flawed:
    Flawed

    Question Type:
    Flawed Parallel Reasoning

    Stimulus Summary:
    Balcony → Fireplace
    Balcony → not 1 bedroom
    Therefore - 1 bedroom → not Fireplace

    Answer Anticipation:
    This Flawed Parallel Reasoning question is pure conditional logic. There's an illegal negation in here (take the contrapositive of the second conditional to see that the argument chains that together with the negation of the first), but since this argument has a conditional logic flaw, we can match the structure instead of worrying about the specific type of conditional logic flaw:

    A → B
    A → not C
    Therefore - C → not B

    Answer Explanation:
    Cat → Fur
    Cat → not Dog
    Therefore - Dog → not Fur
    This matches our diagram from the stimulus perfectly, so this is our answer.

    Key Takeaway:
    When a Flawed Parallel Reasoning question features a conditional logic flaw, spend less time worrying about the specific conditional logic flaw, and more time getting your diagram down. That'll be the fastest way to work through the answer choices!
  4. D
    every cat is a Remaining source text redacted.
    Why choice D is not credited
    Incorrect. Cat → not Dog
    Dog . . . And we're out, as this second conditional doesn't have the same sufficient condition as the first one.
  5. E
    no fish is a Remaining source text redacted.
    Why choice E is not credited
    Incorrect. Dog → Mammal
    Fish . . . And we're out, as this second conditional doesn't have the same sufficient condition as the first one.

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