What is the greatest common divisor of positive intigers m

Question

What is the greatest common divisor of positive intigers m and n?

1) m is a prime number
2) 2n=7m

gmatinjune · Answer

is the answer c

stmt 1 is not suff


stmt 2 - if n = 7 m = 2 then GCD is 1
 if n = 14 m = 4 then GCD is 2

comb. stmts , m can only be 2 and n can only be 7 hence GCD is always 1

Professor · Answer

C...
from i, if m is a prime, n could be equal to m. if m = n, the GCD is n, if not, then 1. so not sufff....

from ii, 2n=7m or n =3.5m.
if so, m cannot be any odd integer. so m is an even integer.
when m = 2, n = 7
when m = 4, n = 14
so GCD varies with respect to m. not suff....

from i and ii, m =2 and n = 7 and GCD is 1.

gmatmba · Answer

Good explanation Prof, I agree its C

ywilfred · Answer

St1:
Insufficient as we have no information about n

St2:
2n = 7m
n = 7m/2

m must be a multiple of 2 since n is an integer and it is equal to 7m/2. If m = 2, then n = 7 and GCD = 1. If m = 4, n = 14, then GCD = 2. Insufficient.

St1 and St2:
We're told m is prime. The only even prime is 2. So m = 2, n = 7, and GCD = 1.

Ans C

remgeo · Answer

Yes, C it is. 

1) m is prime. 

If n = prime, GCD = 1
if n = multiple of m, GCD = m 

Hence insuff

2) 2n=7m

If n=7, m = 2
GCD = 1

If n=14, m=4
GCD = 2

Hence insuff

Combining, gcd is always 1

Hence C

What is the greatest common divisor of positive intigers m

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