• Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • examPAL
    Most awarded test prep in the world
    Now free for 30 days

    Available with Beat the GMAT members only code

    MORE DETAILS
    examPAL
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep

DS on OG

This topic has 6 member replies
magical cook Master | Next Rank: 500 Posts Default Avatar
Joined
30 Jul 2006
Posted:
484 messages
Followed by:
1 members
Upvotes:
2

DS on OG

Post Thu Aug 03, 2006 12:47 am
I would appreciate it if someone could explain this why.... t

hanks in advance!!!
Jane

If X and Y are positive intergers such that X = 8Y + 12, what is the common divisor of X and Y?

1) X=12u where u is an integer
2) y=12z where z is an integer

The answer is B and only question 2 is correct.

  • +1 Upvote Post
  • Quote
  • Flag
gdhiman Junior | Next Rank: 30 Posts Default Avatar
Joined
31 Jul 2006
Posted:
12 messages
Post Sat Aug 05, 2006 10:50 pm
dblazquez wrote:
sorry for the delay
hmm, 12u = 8y + 12, with y = 1 is 20 therefore 2 is common divisor, thats why i was confused... i cant see the mistake

daniel
OK.. so i will try to detail it out.:

If X and Y are positive intergers such that X = 8Y + 12, what is the common divisor of X and Y?

1) X=12u where u is an integer
2) y=12z where z is an integer

In the first option, we have 2 equations:
X=12u & X=8Y + 12
Lets make Y=1, we get x=20.
So there is no common divisor of 1 and 20. (2 is not a common divisor).

In the second option, we have 2 equations:
Y=12z & X=96z + 12.
Lets make z=1, We get Y=12 and X=108.
(So now we have a common divisor for every value of z).

  • +1 Upvote Post
  • Quote
  • Flag
dblazquez Senior | Next Rank: 100 Posts
Joined
29 Apr 2006
Posted:
37 messages
Upvotes:
1
Post Sun Aug 06, 2006 6:51 am
Hey thanks a lot for the explanation, now i see it much clearer... i hate this number properties problem... defintely is B

  • +1 Upvote Post
  • Quote
  • Flag
gdhiman Junior | Next Rank: 30 Posts Default Avatar
Joined
31 Jul 2006
Posted:
12 messages
Post Thu Aug 03, 2006 10:40 am
Good one.

putting in first data to the above equation gets us: 12u = 8y + 12 (u cannot get a common divisor from this).

putting in second data provided we get:
x = 8*12z + 12. So we know 12 divides X for sure, and we also know y is a multiple of 12. So 12 is the common divisor.

Hope i made sense. let me know if u need more clarification.

  • +1 Upvote Post
  • Quote
  • Flag
dblazquez Senior | Next Rank: 100 Posts
Joined
29 Apr 2006
Posted:
37 messages
Upvotes:
1
Post Thu Aug 03, 2006 11:03 am
Hey, i was also trying to solve this good one Smile

Why on the statement I we can state that you cannot get a common divisor from 12u = 8y + 12, what about 2 and four?

  • +1 Upvote Post
  • Quote
  • Flag
gdhiman Junior | Next Rank: 30 Posts Default Avatar
Joined
31 Jul 2006
Posted:
12 messages
Post Thu Aug 03, 2006 7:58 pm
dblazquez wrote:
Hey, i was also trying to solve this good one Smile

Why on the statement I we can state that you cannot get a common divisor from 12u = 8y + 12, what about 2 and four?
Coz what if y = 1. then 2 is not a common divisor or even 4.

  • +1 Upvote Post
  • Quote
  • Flag
dblazquez Senior | Next Rank: 100 Posts
Joined
29 Apr 2006
Posted:
37 messages
Upvotes:
1
Post Sat Aug 05, 2006 12:59 pm
sorry for the delay
hmm, 12u = 8y + 12, with y = 1 is 20 therefore 2 is common divisor, thats why i was confused... i cant see the mistake

daniel

  • +1 Upvote Post
  • Quote
  • Flag

Best Conversation Starters

1 lheiannie07 112 topics
2 ardz24 71 topics
3 Roland2rule 69 topics
4 LUANDATO 53 topics
5 swerve 45 topics
See More Top Beat The GMAT Members...

Most Active Experts

1 image description GMATGuruNY

The Princeton Review Teacher

154 posts
2 image description Rich.C@EMPOWERgma...

EMPOWERgmat

107 posts
3 image description Jeff@TargetTestPrep

Target Test Prep

106 posts
4 image description Scott@TargetTestPrep

Target Test Prep

98 posts
5 image description EconomistGMATTutor

The Economist GMAT Tutor

91 posts
See More Top Beat The GMAT Experts