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DS number theory?

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Source: — Data Sufficiency |
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by ragz » Thu Dec 30, 2010 1:47 pm
Night reader wrote:Is the sum of all factors of a positive integer m less than 130?
(1) m < 130
(2) m > 130
I think C can be eliminated since both can't be used in conjunction.

For Sentence # 1, let's say m=129, the factors of 129 are 1, 3, 43, 129 and clearly the sum is greater than 130. If we suppose, m=13, the factors are 1 and 13 and the sum is less than 130.

So, choices A and D are eliminated as well.

For Sentence #2, for every m>130, the sum of factors will be greater than 130.

So, choice B is the answer.


Can someone tell me if this analysis is correct?
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by Night reader » Thu Dec 30, 2010 1:51 pm
ragz wrote:
Night reader wrote:Is the sum of all factors of a positive integer m less than 130?
(1) m < 130
(2) m > 130
I think C can be eliminated since both can't be used in conjunction.

For Sentence # 1, let's say m=129, the factors of 129 are 1, 3, 43, 129 and clearly the sum is greater than 130. If we suppose, m=13, the factors are 1 and 13 and the sum is less than 130.

So, choices A and D are eliminated as well.

For Sentence #2, for every m>130, the sum of factors will be greater than 130.

So, choice B is the answer.


Can someone tell me if this analysis is correct?
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Ravi.
thank you ragz, please attempt the next question in order
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by lunarpower » Sun Jan 02, 2011 12:51 am
see here:
https://www.beatthegmat.com/ds-number-th ... tml#327962

note also that this problem couldn't be official (and you should probably become a bit less trusting of the source), for the same reasons i mentioned below that post.
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