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Number Properties

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Source: — Data Sufficiency |

by jeffedwards » Tue May 11, 2010 11:26 am
An integer is - any whole number including negatives, zero, and positives.

What the question is basically asking is - Is n a multiple of 29..including 29...or another solution which may work,,but hey i'm at work and this is all i can think of quickly; however, the solutions below hold.

1 - Not sufficient: there are multiple prime numbers that would work and wouldn't work.

2 - Sufficient: What are the prime factors of 116 are 2, 2, 29. Since 29 is the only odd prime, this is the only possible answer. Plug 29 into the equation and you get 0. Zero is an integer..so it's sufficient.
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by jeffedwards » Tue May 11, 2010 11:29 am
jeffedwards wrote:
1 - Not sufficient: there are multiple prime numbers that would work and wouldn't work.
By multiple, i just meant that i can get an integer or a non-integer by using different primes so the statement is not sufficient
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by liferocks » Tue May 11, 2010 4:58 pm
the question is is 29-n/n or 29/n -1 is an integer.Since 29 is a prime number this expression will result in integer if n=1 or 29

From 1.n can be anything like 2,3,5,7...etc--->not sufficient
From 2 ,
116=1x116
=2x58
=4x29
since n is odd factor of 116 ,n is either 1 or 29--->sufficient
"If you don't know where you are going, any road will get you there."
Lewis Carroll
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by raviki8208 » Tue May 11, 2010 10:00 pm
nicajvch wrote:If n is an integer, is (29-n) / n an integer?

(1) n is prime
(2) n is an odd factor of 116
Given: n is integer
Is (29-n)/n = (29/n) - 1 an integer?

using 1) if n is prime, 29/n is not an interger so, sufficient
using 2) n is odd factor of 116= 29*4. => n is 29 so 29/n is an interger so, sufficient

so, Answer is D
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by liferocks » Tue May 11, 2010 10:24 pm
raviki8208 wrote:
nicajvch wrote:If n is an integer, is (29-n) / n an integer?

(1) n is prime
(2) n is an odd factor of 116
Given: n is integer
Is (29-n)/n = (29/n) - 1 an integer?

using 1) if n is prime, 29/n is not an interger so, sufficient
using 2) n is odd factor of 116= 29*4. => n is 29 so 29/n is an interger so, sufficient

so, Answer is D
for condition 1 ,n can be 29(this is a prime number)..so 29-n/n can be integer..can not be concluded anything.
"If you don't know where you are going, any road will get you there."
Lewis Carroll
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