Logical reasoning PrepTest 106 · Section 1 · Question 26

Question prompt

Modern navigation systems, which Remaining source text redacted.
Why the credited answer is right

Credited answer: E

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

Bizarro / Cause & Effect / Strengthen Questions

Stimulus Summary

Modern planes are more susceptible to electronic interference than old ones. Recently, a modern plane veered off course when a laptop was turned on. So modern planes are at risk from passenger electronics.

Answer Anticipation

First, let’s talk about that LEAST instead of an EXCEPT. While linguistically there’s a difference between the two, in practice, the LSAT ends up presenting answers to both that are the same - the correct answer weakens or doesn’t affect the argument. They don’t want to have you make a judgment call about what strengthens an argument more or less, so treat this as a standard Bizarro Must be True question.
Strengthen questions feature a Correlation/Causation flaw more frequently than any other flaw, and that’s particularly true of Bizarro Strengthen questions. Here, the argument concludes that passenger electronics pose a threat to modern planes because they can cause the navigation systems to go haywire - a causal claim. This is based on one example, where the powering on of a laptop coincided with the plane veering off course.
So the argument uses a correlation between this laptop being turned on and the plane veering off course to prove that the laptop caused the problem. When we’re strengthening an argument with a Correlation/Causation flaw, there are common answers to look for:
Explain how the causality works Eliminate an alternative cause (e.g., the pilot didn’t fall asleep at the same time) Show more examples of the cause and effect going together (and since this is based on a single example, this seems like it’ll show up) Bring up a control - no cause, no effect (e.g., modern planes that are empty or don’t have passengers or don’t allow electronics don’t have this problem)
Note that in this Bizarro question, we eliminate any answer that falls into one of those categories!

Answer choices

  1. A
    After the laptop computer Remaining source text redacted.
    Why choice A is not credited
    This answer shows that when the supposed cause was removed (laptop off), so was the effect. That strengthens the argument, so we can eliminate this answer.
  2. B
    When in use all Remaining source text redacted.
    Why choice B is not credited
    This answer explains how the passenger electronics can cause the plane to go haywire, so it strengthens the argument. Another elimination!
  3. C
    No problems with navigational Remaining source text redacted.
    Why choice C is not credited
    This answer establishes a control - no cause, no effect. That strengthens the argument, so we can eliminate it.
  4. D
    Significant electromagnetic radiation from Remaining source text redacted.
    Why choice D is not credited
    This answer establishes that the cause and effect are colocated, allowing the causality to happen, thus strengthening the possibility of it.
  5. E
    Planes were first equipped Remaining source text redacted.
    Why choice E matches the stem
    This answer doesn’t connect directly to the problem that the combination of these two is supposed to lead to, so we don’t know if this impacts the argument. If we learned that, around this time, planes started to have the navigation problems noted when they hadn’t before, then this would strengthen the argument (cause and effect showing up at the same time). But it doesn’t, so this answer doesn’t affect the argument and is thus correct.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A 8%
  2. B 9%
  3. C 6%
  4. D 5%
  5. E Credited 72%

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