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Each week we'll be posting several questions from The Official Guide for GMAT® Review, 13th Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.
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Since t = 11 seconds represents time, one can immediately eliminate answers C,D and E, because they don't have units of time. (C) x/(ty) has units of 1/time (D) t/(xy) has units of time/speed squared, which finally is time cubed/distance squared (E) xy/t has units of speed squared/time, which finally is distance squared/time cubed
To choose between (A) and (B), we should keep in mind that time is distance/speed. Since the distance in our case is x, it should appear in the numerator.
Hence, Answer A. _________________
PhD in Applied Mathematics Love GMAT Quant questions and running.
This problem is testing us on the Rate x Time = Distance relationship. This relationship also tells us that Rate = Distance/Time and Time = Distance/Rate.
Ultimately, we are looking for how many seconds it will take Juan to run x yards. Thus, the equation we’ll use is: Time = Distance/Rate. We know the distance is x yards, and we need to find Juan’s rate.
We can find Juan’s rate as follows: Rate = Distance/Time = y yards/11 seconds
Using that rate, we need to determine how long it takes him to run x yards at the same rate. So we have:
Time = Distance/Rate
Time = x yards/(y yards/11 seconds)
Time = (x yards) x (11 seconds/y yards)
Time = 11x/y seconds
Answer A. _________________
Jeffrey Miller Jeffrey Miller Head of GMAT Instruction
Re: If Juan takes 11 seconds to run y yards, how many seconds
27 May 2016, 07:18