Logical reasoning PrepTest 140 · Section 1 · Question 17

Question prompt

If a motor is Remaining source text redacted.
Why the credited answer is right

Credited answer: B

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

Question Type

Must Be True Questions / Sufficient & Necessary Questions

Answer choices

  1. A
    If a motor can Remaining source text redacted.
    Why choice A is not credited
    Incorrect. This answer is an illegal reversal of the conditional chain.
  2. B
    None of the motors Remaining source text redacted.
    Why choice B matches the stem
    Correct. Argument or Facts:
    Facts

    Question Type:
    Must Be True

    Stimulus Summary:
    Sound-insulated → Quiet enough for home appliances
    Quiet enough for home appliances → OK for institutional settings
    EM Industries: not Quiet enough for home appliances

    Answer Anticipation:
    Let's get these conditionals chained together and then take the contrapositive so we can apply it to EM Industries:

    Sound-insulated → OK for home → OK for institutions
    not OK for institutions → not OK for home → not Sound-insulated

    With these conditionals, we can see that EM Industries, in making motors not question enough for home appliances, must not make sound-insulated motors. Also, we should note that we can't draw any conclusion about whether their motors are good or not for institutions since the fact we learn about them doesn't trigger any sufficient condition about institutional use.

    Answer Explanation:
    The contrapositive of the first conditional is triggered by the fact about EM Industries, thus guaranteeing that their motors that aren't quiet enough for home use aren't sound-insulated.

    Key Takeaway:
    This question is a straight-forward conditional Must Be True question, so it's a great gauge of your conditional skills. If you were able to quickly work through this question and get it correct (60-65 seconds), then your conditional skills are probably in a good place. If not, keep drilling those conditionals!
  3. C
    At least some of Remaining source text redacted.
    Why choice C is not credited
    Incorrect. There are two sufficient conditions that guarantee a motor is OK for institutional use: sound insulation, or home use. EM motors aren't good for home use, and that tells us they aren't sound-insulated, so we can't guarantee any are good for institutional settings (note that we can't rule it out, either).
  4. D
    If a motor is Remaining source text redacted.
    Why choice D is not credited
    Incorrect. This answer is an illegal reversal of the first conditional.
  5. E
    None of the motors Remaining source text redacted.
    Why choice E is not credited
    Incorrect. There are no sufficient conditions for not OK for institutions, so this answer couldn't even be drawn based on the stimulus.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A 3%
  2. B Credited 75%
  3. C 2%
  4. D 2%
  5. E 18%

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Discussion

  • Why B? 2 replies

    Started by Eugene

  • Why not E 1 reply

    Started by franco

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