Critical Reasoning

For the last five years, the XYZ Courier Company has made regular delivery trips between Town A and Town B. The average time taken by the company's drivers to drive the round trip between the two towns, excluding the time taken for loading, unloading, and delivery, over that period has been 80 minutes. John, a driver for XYZ, needs to make a personal trip between the two towns; he figures that he should allow approximately 80 minutes for the round trip.

Which of the following, if true, does not call John's conclusion into question?

A) The route between Town A and Town B has been plagued by increasing congestion over the last five years, as the area's population has doubled during that time.

B) Most of XYZ's courier vehicles are heavy trucks, for which speed limits are lower than for passenger vehicles.

C) Many of the packages carried by XYZ between Town A and Town B are large, high-security packages, for which the processes of loading, unloading, and delivery can take up to half the length of the trip itself.

D) John will make his personal trip at an hour when XYZ does not make delivery trips.

E) Before a freeway was built between Town A and Town B two years ago, the only routes between the two towns were state highways with multiple traffic lights and reduced-speed downtown zones.

OA - C. I see why.

But what's wrong with E? If, for the past two years, the freeway is built, it means that John needs less amount of time to complete his round trip. The question is not asking us about the exactness of time, but an average time. If it takes 5 hours to go from Boston to NYC, then scheduling 6 hours drive time should be okay. Isn't it?

Please help!

-Voodoo Child

between C and E.

E - average = 80 total for 5 years = 80*5 = 400
1st year +2nd + 3rd = 400- (4th + 5th year= 80 each suppose) meaning,
even if the free way is built, John's approximation is correct.
Hence POE.

C call into question the value 80 itself. It means,the value may not be 80,but more than that say 80+40 = 120 or more.
Hence,John's assumption is most definitely wrong.Hence an OA.

John's conclusion : I will take 80min to make the round trip

A) Traffic is increasing so time may go >80min
B) Truck speed limit will be < car's speedlimit. John(A transportor) may be Jason statham and may take only 20min. Kidding but this is valid.
E) Yes you are right. we may need some assumption to get this option out. John may choose differnt routes resulting in differnt times..; 70min, 80 min or even 120min...

E is a kind of data insufficiency

Conclusion: John plans 80 min for the round trip

Evidence: Company Drivers take 80 min on average.

Assumption: "On average" is not an issue, there isn't a reason the trucks move more quickly/slowly than normal cars

Question: What does NOT weaken the question?

Prediction: Eliminate answer choices that show a difference between cars/trucks or show that the average is not likely not be true for John

A - more congestion now = affects average
B - shows diff. in speed
C - the loading/unloading/and delivery was not part of the time --- this is correct
D - this would make the stats irrelevant for John
E - this would have made the times for the first 2 years slower than today, and affects average

Ron,
Thanks for replying. I didn't follow the explanation. Let's take an example:

Time to travel from NYC to Boston takes 5 hours (say - based on a 5-year average).
Now, let's assume that IS-84 was built two years ago. Hence, the driving time would be less than 5 hours because the first three years' driving time would have increased the average.

How does this weaken the conclusion? Are you saying that it weakens because John han't calculated the "average" correctly, accounting the past five years instead of the last two years?

Please help me