It is currently 24 Sep 2017, 18:04

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If x and y are positive integers such that x=8y+12, what is

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Current Student
User avatar
Joined: 11 May 2008
Posts: 555

Kudos [?]: 216 [0], given: 0

If x and y are positive integers such that x=8y+12, what is [#permalink]

Show Tags

New post 04 Sep 2008, 20:21
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

If x and y are positive integers such that x=8y+12, what is the greatest common divisor of x and y?
(1) x is divisible by 12.
(2) y is divisible by 12.

Kudos [?]: 216 [0], given: 0

Director
Director
avatar
Joined: 23 Sep 2007
Posts: 782

Kudos [?]: 227 [0], given: 0

Re: GCD [#permalink]

Show Tags

New post 04 Sep 2008, 21:23
arjtryarjtry wrote:
If x and y are positive integers such that x=8y+12, what is the greatest common divisor of x and y?
(1) x is divisible by 12.
(2) y is divisible by 12.


B
because statement 2 would result in x=12n, where n is an odd integer, y =12a if a is an even integer, n is not divisible by a, if a is an odd integer, n still will not be divisible by a. thus the GCD is 12.

Kudos [?]: 227 [0], given: 0

SVP
SVP
avatar
Joined: 17 Jun 2008
Posts: 1539

Kudos [?]: 278 [0], given: 0

Re: GCD [#permalink]

Show Tags

New post 05 Sep 2008, 00:38
I used numbers to get the answer B.

Stmt 1: x is divisible by 12...that means two 2's and one 3 is required. In 8y+12, 12 is divisible by 12, but in order for 8y to be divisble by 12, y has to be a multiple of 3.

Thus, y can be 3, 6,9,12,15,18...etc and GCD of x and y can be 3, 6, 12,...etc....not sufficient.

Stmt2: y is divisible by 12....and y is positive....hence y is a multiple of 12

Values of y 12,24,36,48...
Values of x 12X9, 12X17, 12X25, 12X33.....

Thus, GCD between X and Y will be 12. Hence, sufficient.

Kudos [?]: 278 [0], given: 0

Senior Manager
Senior Manager
avatar
Joined: 16 Jul 2008
Posts: 289

Kudos [?]: 16 [0], given: 4

Schools: INSEAD Dec'10
Re: GCD [#permalink]

Show Tags

New post 05 Sep 2008, 01:06
From the stem, we have that x is divisible by 4 and definitely not divisible by 8 (x divided by 8 gives a remainder of 4). Also, y = (x-12)/8. Therefore x = 4*5; 4*7; 4*9; .... 4 times odd number. Y can be anything. Therefore, Statement 1 cannot be sufficient by itself, becuase it only gives us information on x and not on y.

Jumping straight to statement 2), it gives us that y is divisible by 12. This means that y is at least 12 and x is at least 12*9 and the GCD could be 12.

For y=n*12, x=(8*n+1)*12. No way the GCD is n*12. Answer should be B.
_________________

http://applicant.wordpress.com/

Kudos [?]: 16 [0], given: 4

VP
VP
avatar
Joined: 17 Jun 2008
Posts: 1378

Kudos [?]: 392 [0], given: 0

Re: GCD [#permalink]

Show Tags

New post 05 Sep 2008, 21:58
scthakur wrote:
I used numbers to get the answer B.

Stmt 1: x is divisible by 12...that means two 2's and one 3 is required. In 8y+12, 12 is divisible by 12, but in order for 8y to be divisble by 12, y has to be a multiple of 3.

Thus, y can be 3, 6,9,12,15,18...etc and GCD of x and y can be 3, 6, 12,...etc....not sufficient.

Stmt2: y is divisible by 12....and y is positive....hence y is a multiple of 12

Values of y 12,24,36,48...
Values of x 12X9, 12X17, 12X25, 12X33.....

Thus, GCD between X and Y will be 12. Hence, sufficient.

good Explanation!!
_________________

cheers
Its Now Or Never

Kudos [?]: 392 [0], given: 0

Re: GCD   [#permalink] 05 Sep 2008, 21:58
Display posts from previous: Sort by

If x and y are positive integers such that x=8y+12, what is

  post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.