Online Lab #7 DS Rephrasing Q40 Question

[minaymartinez]

Hello there,

If the question is "How many miles long is the route to Houghton to Callahan?" (so this is a Distance question, ie D=RT).

And one of the Data Sufficiency statements says, "It will take 11 hours to travel the first half of the route at an average rate of 25 miles per hour."

Manhattan GMAT says this is SUFFICIENT, via the formula:
D= RT
0.5D = 25(11)

What trips me up in this statement though, is the part that says "first half of the route." I thought we couldnt assume that the 2nd half of the route was the same rate? That was why my initial answer was INSUFFICIENT.

If a statement is worded this way, can we assume that the second half of the route has the same rate (or time) and therefore we are able to get the total distance?

[RonPurewal]

hi,
this is the wrong folder for this thread. i've locked the thread; if you have any further questions, please post them in the correct folder (i.e., the "mgmat non-cat" folder). thanks.

--

remember -- the most important thing in data sufficiency is not losing sight of THE GOAL in the problem.
in this problem, the goal is the total distance. if you can find that, then it doesn't matter whether you can find anything else.

so...
you are right that you can't assume anything about how the second half of the route is traveled.
on the other hand, you don't have to. from the given statement, you can find how long "the first half of the route" is -- and so you've got exactly half the total distance.
if you have half the total distance, then you have the whole distance (just multiply it by 2).

don't forget what the question is asking in the first place!