PrepTest 119

[lcid:3573] Prep Test 119 LSAT — Logical Reasoning — S2 Logical reasoning

Question prompt

Detective: Laser–printer drums are 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.

Argument or Facts

Argument

Valid or Flawed

Flawed

Question Type

Weaken Questions

Stimulus Summary

Laser-printer drums can get nicks that cause blemishes on printed pages, so if we can match a blemish to a nick on a drum, we can identify the specific printer that created a document.

Answer Anticipation

Sometimes, an argument suggests a parallel that you can use to help you find the answer. Here, this very much sounds a lot like matching a fingerprint to identify a suspect.
However, there’s an important piece of information about fingerprints that we don’t know about drum nicks - they’re unique. It’s possible that drum nicks are repeated between drums. Maybe they develop when the drum is being made, or a tool that moves them can cause the same nick in multiple drums. Any answer that calls into question the uniqueness of the pattern of nicks on a drum will weaken this argument.

Answer choices

  1. A
    Criminals are unlikely to Remaining source text redacted.
    Why choice A is not credited
    The conclusion states that this process can lead investigators to the printer, not the criminal, so this answer has no effect on the argument.
  2. B
    Drum nicks are usually Remaining source text redacted.
    Why choice B is not credited
    This answer is trying to make you think that tracing the printer with these marks isn’t reliable, as the argument states, because of the skill required. But someone with the skill may be able to reliably determine their size and shape, so this answer doesn’t hurt the argument.
  3. C
    The manufacturing process often Remaining source text redacted.
    Why choice C matches the stem
    If multiple drums have the same “nickprint”, then finding the “precise printer” that printed a given document with that nick wouldn’t be possible just based on finding a match between the paper and the drum. This answer calls the conclusion into question, so it’s correct.
  4. D
    Blemishes on documents are Remaining source text redacted.
    Why choice D is not credited
    The conclusion is conditioned on there being a blemish on a page with a nick on a drum, so if a blemish is invisible, then the conclusion wouldn’t apply to that situation, and thus this answer doesn’t weaken the argument. This would be correct if the argument concluded that any document (or any document with a blemish) can be matched back to a printer.
  5. E
    Most suspicious documents are Remaining source text redacted.
    Why choice E is not credited
    The conclusion is about “suspicious laser-printed documents,” so documents produced on other machines are out of scope.

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