GMAT Prep1

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GMAT Prep1

by fsutanto » Sun Sep 26, 2010 9:26 am
What is the greatest common divisor of positive integers m and n?

(1) m is a prime number
(2) 2n = 7m


The correct answer is [spoiler](c)[/spoiler], but what's the logic? Anyone? Thanks!
Source: — Data Sufficiency |

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by this_time_i_will » Sun Sep 26, 2010 10:10 am
I: not sufficent, as it does not talk about n.
II: many values possible for m & n. for e.g. n=7 & m=2 or n=14 and m = 4 and so on.

I and II:
As per II, 7m should be even and as per I m is prime. These two conditions hold only for m=2.
Now if m = 2, n sud be 7. so the greatest common factor is 1.