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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.
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