Okay, so the passage break down tells us that he plans to increase tolls by 50% and this will lead to 50% increase in revenue. This means that the distance traveled by people which is toll-worthy has remained unchanged.

The stimulus says
he highway commission of a certain state is considering a 50 percent increase in the 10-centers-per-mile toll for vehicles using its toll highway.

Conclusion is
the toll increase will increase the annual revenue generated by the toll highway by at least 50 percent per year.

so the percentage of increase in toll = percentage of increase in revenue
i.e total distance traveled on the bridge is constant. its the total distance because the toll is calculated on per mile basis. not the number of trips or average length of the trips or the number of travelers on the bridge

So the ans is E

Total distance travelled needs to be constant inorder to 50% increase in revenue. So E.
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+1 E
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I like this question +1
I did it right

Awesome Question.
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Argument : If you love long trips, you love the GMAT.
Conclusion : GMAT is long journey.

What does the author assume ?
Assumption : A long journey is a long trip.

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The question is fairly straightforward. A 50% increase in the per-mile toll is brought about. In order to increase the annual revenue, the mandated condition is: Number of miles remain same, or increases.

In order to finance road repairs, the highway commission of a certain state is considering a 50 percent increase in the 10-centers-per-mile toll for vehicles using its toll highway. The highway commissioner claims that the toll increase will increase the annual revenue generated by the toll highway by at least 50 percent per year.

Which of the following is an assumption on which the highway commissioner's claim depends?

(A) The amount of money required annually for road repairs will not increase from its current level. - Irrelevant. Why do we care about the road repairs? We are talking about revenue generated by tolls, not the "profit" or "breakeven" of the highway authorities.
(B) The total number of trips made on the toll highway per year will not decrease from its current level. - Information about number of trips without average mileage per trip is redundant.
(C) The average length of a trip made on the toll highway will not decrease from its current level. As stated above, information about mileage without the number of trips will not serve any purpose for what we are asked to find here.
(D) The number of drivers who consistently avoid the highway tolls by using secondary roads will not increase from its current level. This is a very indirect option, and we can probably hold on to see if there's a better answer.
(E) The total distance traveled by vehicles on the toll highway per year will not decrease from its current level. This is the correct answer. If you are looking a toll that is charged per mile, and you know the total distance traveled by the cars stays the same, in essence you're saying that there's a 50% increase in the revenues. Think about numerical figures:

Let's say total distance traveled before was 100 miles. This stays the same now. Let's assume the toll per mile was $1 initially and now it's $1.5. Original revenue was $100 and now revenue is $150, which is 50% more than the original revenue. This statement directly supplements the question and hence is the right choice.


TehJay's Question was:

B and D give you one part of the information and fail to give you the rest. Knowledge about the number of trips without average distance traveled per trip or vice versa is not useful in evaluating this argument. Okay, as per B the number of trips has increased from say, 50 to 100. But the average length of the trip has gone down from 3 miles to 1 mile, this means, in effect, the toll collected has reduced. Similarly for the other situation. Let's say the average miles per trip has gone up, but it's in a way that the number of trips have gone down. So each piece by itself is insufficient to frame a conclusion. You can't afford to assume whatever you need to justify an answer or in this case, answers that seems right. Thinking objectively about all possible constraints will help resolve most issues on tricky questions like these. And in the end, sometimes, you just have to go with the best option, since it might feel like multiple options are correct sometimes.

'Thinking objectively about all possible constraints will help resolve most issues on tricky questions like these.'
thanks whiplash
that is a very good practice .all possible constraints have to be considered. this was definitely a tricky question,
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