Logical ReasoningDifficulty: Easy

PT147 S1 Q1 Explanation

After a major toll highway introduced

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsParadox

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Stimulus

After a major toll highway introduced a system of electronic toll paying, delays at all of its interchanges declined significantly. Travel time per car trip decreased by an average of 10 percent. Tailpipe pollution for each trip decreased commensurately. vehicles on that highway did not decrease measurably.

What this question is testing

Paradox

Your task

Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.

Common trap

Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.

Winning move

Predict what a right answer must do, then test each choice against the conclusion-evidence gap.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
1.

Which one of the following, if true, most helps to resolve the apparent discrepancy in

Answer choices

  1. Opposite (if anything)0% picked this

    The highway began charging higher tolls when it switched to electronic

    Higher tolls would potentially discourage drivers from using the highway. We would expect that to decrease the total air pollution.

  2. Too Weak: sometimes2% picked this

    Even after the switch to electronic toll paying, there were sometimes long delays at

    This answer could be something that the stimulus already takes into account. We're told that delays at all interchanges declined significantly. That can still be true, and still contribute to their being less pollution, even if there are still "sometimes" long delays.

  3. Correct95% picked this

    The prospect of faster, more convenient travel induced more drivers to

    Why this is right

    If more drivers used the highway there would be an increase in pollution. The decrease in pollution per trip might not be enough to offset this increase caused by more drivers, so the total amount of pollution could easily stay the same.

    Skill tested: Paradox · how this choice captures the argument's function is the move to repeat next time.

  4. Too Weak1% picked this

    Travel time on the highway for car trips under 30 kilometers (18.6 miles) did

    This answer could be something that the stimulus already takes into account. We're told that travel time per car trip decreased by an average of 10 percent. That average would already account for any travel times that didn't decrease. If travel times for trips under 30 km didn't decrease, travel times for other trips would have decreased enough to produce an average decrease of 10 percent. The average decrease of 10 percent is more relevant than the travel time for any individual trip.

  5. Too Weak: some1% picked this

    Some drivers did not switch to the electronic system but instead continued to use cash to pay their

    Based on the information that we're given in the stimulus, it seems that a significant number of drivers did switch to the electronic system. That could very well be what caused the decreases in delays at interchanges, average total time per trip, and tailpipe pollution. And this could all be true even if "some" drivers did not switch to the electronic system. This answer could easily be something that the stimulus already takes into account.

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