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Source: — Data Sufficiency |
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by mals24 » Wed Nov 26, 2008 6:28 am
IMO C

St 1 m is prime.
m =3 n = 4 GCD = 1
m = 2 n = 4 GCD = 2
So since we don't have information about n---INSUFF

St 2 2n = 7m
m = 4, n = 14 GCD = 2
m = 2, n = 7 GCD = 1

Combining 1&2
m is prime.
The only prime number that will satisfy St 2 is 2
So m=2, n=7 GCD =1

C
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by rohangupta83 » Wed Nov 26, 2008 6:55 am
mals24 wrote:IMO C

St 1 m is prime.
m =3 n = 4 GCD = 1
m = 2 n = 4 GCD = 2
So since we don't have information about n---INSUFF

St 2 2n = 7m
m = 4, n = 14 GCD = 2
m = 2, n = 7 GCD = 1

Combining 1&2
m is prime.
The only prime number that will satisfy St 2 is 2
So m=2, n=7 GCD =1

C
can GCD actually be 1?
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by scoobydooby » Wed Nov 26, 2008 7:11 am
yes for numbers that are prime to each other
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by mals24 » Wed Nov 26, 2008 7:15 am
can GCD actually be 1?
Yes like scoobydooby said, GCD of all prime numbers is 1.

2 = 2*1
7 = 7*1

The highest common factor of 2 and 7 is 1.
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by austin » Wed Nov 26, 2008 7:17 am
GCD of 2 numbers (x,y) is the greatest/biggest number that can divide both x and y.

(x,y) GCD/HCF

2,3 1
4,5 1

RESULT: The HCF of two consectutive positive numbers is 1

2,5 1
7,23 1

RESULT: The HCF of two prime numbers is 1

IF THE HCF OF TWO NUMBERS IS 1, THEN THE TWO NUMBERS ARE CO-PRIME ie. 2 and 3 are co-prime.

Hope I have given some clarity...
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by rohangupta83 » Wed Nov 26, 2008 8:51 am
mals24 wrote:
can GCD actually be 1?
Yes like scoobydooby said, GCD of all prime numbers is 1.

2 = 2*1
7 = 7*1

The highest common factor of 2 and 7 is 1.
I agree with C then :)

good to have concepts refreshed
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by cramya » Wed Nov 26, 2008 9:01 am
One more vote for C) approach same as Mals24.


GCD : 1 (for any 2 primes this is the gcd)
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