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# Is 30 a factor of n? (1) 30 is a factor of n^2 (2) 30 is a

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Is 30 a factor of n? (1) 30 is a factor of n^2 (2) 30 is a [#permalink]

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04 Sep 2006, 01:31
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Is 30 a factor of n?

(1) 30 is a factor of n^2
(2) 30 is a factor of 2n
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04 Sep 2006, 02:04
In statement 2: n could be 15. INSUFF

I'll take (A)
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04 Sep 2006, 05:44
It must be C..

A. Is insufficient as n can be sqrt(30)

B. Is insuficient as n can be 15.

A and B together satisfies the condition...
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04 Sep 2006, 09:56
Agree with C. In A n=sqrt30
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04 Sep 2006, 10:38
how can it be A?

we dont even know if N is an integer?

(1) N^2=30M,

so we know that N^2 has prime factors, 2,3 and 5..but we dont know if N is an integer or not...N cud sqrt(30)..Insuff

(2)..well everyone else explained why it isnt suff...

C..together..cause (2) tells us that N is an integer and has definetly prime factors 3 and 5...statemnet confirms that N has 2, 3 and 5 as prime factors...thus togehter they are sufficient..

C it is..
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04 Sep 2006, 10:45
OA IS C

Thanks folks
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04 Sep 2006, 13:58
ps_dahiya wrote:
Straight A.

Silly mistake.
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SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008

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04 Sep 2006, 22:15
another one -
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04 Sep 2006, 22:34
This questions never gets old

Here is a detailed explanation from the expert - HongHu
http://www.gmatclub.com/phpbb/viewtopic.php?t=16160
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- Bernard Edmonds

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05 Sep 2006, 05:44
how can it be C

if n= 15 , then from St2, 30 is factor of 30, but 30 is not a factor of n (15) or n^2 ( 225). Only if n = 30, 60, 90 then n is factor of n^2 and n and also satisy statement 2.

Since from both statements you can not get a clear yes/ no answer, it must be E
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05 Sep 2006, 06:01
Jainan 24 i will try to explain it to you in details

Is 30 a factor of n?

(1) 30 is a factor of n^2
(2) 30 is a factor of 2n

From one

n^2 = 30m ie n = sqrt of 30m if m = 1 n is not integer if m=30 therfore n=30......thus insuff

from 2

2n = 30k thus n = 15 k if k is odd thus 30 is not a factor of n only when k is even that this is true ( ie k = 2z).....insuff

C scinario

from one
n^2 is even (15*2m)

from two

n = 15k ie : n^2 = 15^2*k^2 and since from one n^2 is even

therfore 15^2*k^2 is even , we know that odd*even = even,

15^2 is odd ie:(odd*odd) therfore k^2 is even thus k is even ie = 2z

therfore both together are enough
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05 Sep 2006, 06:28
05 Sep 2006, 06:28
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