Q1 - After a major toll highway introduced

[mshinners]

Question Type:
Explain a Result

Stimulus Breakdown:
This highway introduced Easy Pass. Aftewards, delays decreased, travel time decreased, tailpipe pollution decreased per trip. But total air pollution stayed the same ("didn't decrease measurably").

Answer Anticipation:
The discrepancy here is that, despite each individual car spending less time on the highway and polluting less, the total amount of pollution didn't change much. We need an explanation for how that could happen, and the only one that comes to mind is that there are more cars on the road. The increased number of cars could balance out the decrease in pollution per car.

Correct answer:
(C)

Answer choice analysis:
(A) If anything, the opposite. Even if you make the jump to saying that a higher price would drive people away from the highway (see what I did there?), that would, if anything, make the discrepancy worse - fewer cars polluting less should reduce pollution.

(B) Irrelevant. We are told that the average delay decreased, so it doesn't matter if there are occasional long delays.

(C) Bingo. An increase in the number of cars could balance out the decrease in pollution per car. Think about a birthday present for the boss–the more people who chip in for that fancy new neck tie, the less each person has to contribute.

(D) Irrelevant. This answer is similar to (B), in that we still know about the average went down, so a few trips that took longer won't help explain the overall trend.

(E) Irrelevant, and too weak. "Some" could be just 3, and that wouldn't move the speedometer all that much (again with the puns!). Also, again, we still know the average amount of pollution per car went down. That average includes the cars that didn't make the switch, so this aligns with, but doesn't explain, the situation.

Takeaway/Pattern: When the LSAT talks about averages and rates, think about how that would impact totals. Here, the average per car went down. Since it's an average, it's already taken into account outliers, so we can usually rule out those answers. Since it's a rate (per car), we should consider whether the total number of cars changed.

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