carcass wrote:

If a rocket can travel \(\frac{x}{5}\) miles every y seconds, how many miles can it travel in z minutes?

A. \(\frac{xy}{5z}\)

B. \(\frac{xz}{5y}\)

C. \(\frac{xyz}{6}\)

D. \(\frac{12xy}{z}\)

E. \(\frac{12xz}{y}\)

1) Algebraic method :-\(\frac{x}{5}\) in y seconds

so \(\frac{x}{5y}\) in 1 second

or \(\frac{60x}{5y}=\frac{12x}{y}\) in 60 seconds or 1 minute

therefore in z minutes \(\frac{12xz}{y}\)

2) substitution take x = 5, so that 5/5 becomes 1

take y = 60 seconds, so that it becomes 1 minute

take z = 1

so 5/5 = 1 in 60 seconds or 1 minute which is same as z minute

substitute in choices and you should get 1 as the answer..

A. \(\frac{xy}{5z}......\frac{5*60}{5*1}\neq{1}\)

B. \(\frac{xz}{5y}..........\frac{5*1}{5*60}\neq{1}\)

C. \(\frac{xyz}{6}...........\frac{5*60*1}{6}\neq{1}\)

D. \(\frac{12xy}{z}.........\frac{12*5*60}{1}\neq{1}\)

E. \(\frac{12xz}{y}..........\frac{12*5*1}{60}=1\)...Answer

E

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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372

2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

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