Logical Reasoning

PT147 · S1 · Q1 After a major toll highway introduced

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After a major toll highway introduced a system of electronic toll paying, delays at all of its interchanges declined significantly.

Given that...

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.

How can it be that...

The total air pollution from vehicles on that highway did not decrease measurably.

Evaluate

If we look at all of the changes which occurred after the electronic toll system was introduced, it seems like they would cause the total air pollution to decrease. Why didn't that happen?

We know that travel time and tailpipe pollution decreased for each trip. But what if there were significantly more trips? That could result in the total amount of pollution remaining the same.

Goal

A correct answer might suggest that a greater number of trips were made after the electronic toll system was introduced. Beware of answers which simply reinforce the idea that there was less pollution per trip without explaining why there was no measurable decrease in total air pollution.

1.

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

  1. The highway began charging higher

    Opposite (if anything)

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

    1% picked this

  2. Even after the switch to

    Too Weak: sometimes

    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.

    2% picked this

  3. Correct

    The prospect of faster, more

    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.

    95% picked this

  4. Travel time on the highway

    Too Weak

    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.

    1% picked this

  5. Some drivers did not switch

    Too Weak: some

    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.

    1% picked this

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