GCD

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Tryingmybest: Master | Next Rank: 500 Posts; Posts: 168; Joined: Thu Nov 13, 2008 4:34 am; Location: Pittsburgh; Thanked: 9 times

GCD

by Tryingmybest » Wed Mar 25, 2009 7:34 am

What is the greatest common factor of positive integers x and y?

(1) The greatest common factor of x/2 and y/2 is 5.
(2) x and y are even.

OA after some discussions

Last edited by Tryingmybest on Wed Mar 25, 2009 3:29 pm, edited 1 time in total.

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Source: Beat The GMAT — Data Sufficiency | Wed Mar 25, 2009 7:34 am

karmayogi: Master | Next Rank: 500 Posts; Posts: 467; Joined: Thu Nov 06, 2008 10:19 pm; Thanked: 27 times; Followed by:1 members

Re: GCD

by karmayogi » Wed Mar 25, 2009 7:53 am

Tryingmybest wrote:What is the greatest common factor of positive integers x and y?

(1) The greatest common factor of and is 5.
(2) x and y are even.

OA after some discussions

I guess, statement#1 has typo error. If no error then IMO E

Each soul is potentially divine. The goal is to manifest this divine within.
--By Swami Vivekananda

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Tryingmybest: Master | Next Rank: 500 Posts; Posts: 168; Joined: Thu Nov 13, 2008 4:34 am; Location: Pittsburgh; Thanked: 9 times

by Tryingmybest » Wed Mar 25, 2009 4:20 pm

Sorry.... edited the post now

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Mustang: Senior | Next Rank: 100 Posts; Posts: 43; Joined: Fri Jul 18, 2008 9:20 pm; Thanked: 2 times; GMAT Score:770

by Mustang » Wed Mar 25, 2009 4:46 pm

IMO A

if GCD of x/2 and y/2 is 5 then essentially we are multiplying both (x/2) and (y/2) by 2 to get x and y. therefore 2 becomes a common factor of both x and y and so the GCD of x and y will be 2* [GCD of (x/2) and (y/2)].