Thread: Integers
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Old 07-24-2008, 02:52 AM   #2 (permalink)
Retake_GMAT
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First Attack 450 by writing it in terms of powers of primes.

450= 45*10=9*5 *5*2=(3^2)*(5^2)*(2)
(3^2)*(5^2)*(2) * y = n^3.

If we take cube root, we must get both n and y as integers ( Question stem says that).

hence we need to have 3 as power on the primes 3,2,5.

We already have 3^2 , 5^2, hence y = 3*5*2^2.

If y=3*5*2^2. should be an integer.

Ans B
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