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GMAT practice test #1 question

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john_haddock
 Post subject: GMAT practice test #1 question
 Post Posted: Wed May 20, 2009 6:22 pm 
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Course Students


Posts: 6
In n and p are positive integers and 450n=n^3, which of following must be integer?

i y/(3 times 2^2 times 5)
ii. y/(3^2 times 2 times 5)
iii. y/(3 times 2 times 5^2)
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kevinmarmstrong
 Post subject: Re: GMAT practice test #1 question
 Post Posted: Thu May 21, 2009 1:44 pm 
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Posts: 28
If 450y is a perfect cube, when 450y is written as a product of prime numbers, the exponents on the prime factors must all be multiples of 3.

Since 450 = 2 * 3^2 * 5^2, y must be a multiple of 2^2 , 3 and 5.

Thus only i must be an integer
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RonPurewal
 Post subject: Re: GMAT practice test #1 question
 Post Posted: Fri May 22, 2009 6:49 am 
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ManhattanGMAT Staff


Posts: 7146
here are some previous postings on this question.

if-n-and-y-are-positive-integers-and-450y-n-3-t4311.html

if-n-and-y-are-positive-integers-and-450y-n-3-which-of-t279.html
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