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GMAT Prep DS Question

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khwaja.shoaib
 Post subject: GMAT Prep DS Question
 Post Posted: Sun Nov 22, 2009 3:28 am 
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Students


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What is the remainder when the positive integer n is divided by the positive integer k, where k > 1


(1) n = (k+1)^3
(2) k = 5


OA = A

Can someone please explain this?
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amit2k9
 Post subject: Re: GMAT Prep DS Question
 Post Posted: Tue Nov 24, 2009 11:37 pm 
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Posts: 18
Substitute k = 2,3,10.

Each time you will get 1 as remainder.So the OA.

thanks
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pritesh.suvarna
 Post subject: Re: GMAT Prep DS Question
 Post Posted: Sun Nov 29, 2009 8:56 pm 
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Students


Posts: 8
(1) n = (k+1)^3 / k

Since the numerator is k+1 and denominator = k, the remainder will always be 1

A - Suff

(2) k = 5

n not defined.

Ans = A

Thanks
Pritesh
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gayatri.ganpaa
 Post subject: Re: GMAT Prep DS Question
 Post Posted: Mon Nov 30, 2009 12:50 am 
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Students


Posts: 5
Another way of solving this --
a) If you expand (k+1)^3 --> k^3+3k^2+3k+1 When you divide n/k- all the terms are divisible by k, except for 1. Therefore, remainder is 1.

b) does not give you any information about n
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Ben Ku
 Post subject: Re: GMAT Prep DS Question
 Post Posted: Thu Dec 24, 2009 6:54 pm 
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ManhattanGMAT Staff


Posts: 823
gayatri.ganpaa wrote:
Another way of solving this --
a) If you expand (k+1)^3 --> k^3+3k^2+3k+1 When you divide n/k- all the terms are divisible by k, except for 1. Therefore, remainder is 1.


This is a good algebraic proof for statement 1.

The plugging in numbers approach works; however, you cannot plug in and evaluate all values. I would suggest to look for the algebraic approach first.

_________________
Ben Ku
Instructor
ManhattanGMAT
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