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.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

If x and y are positive integers, is x/y an integer? (1) [#permalink]

Show Tags

09 Sep 2007, 19:34

00:00

A

B

C

D

E

Difficulty:

(N/A)

Question Stats:

100% (00:00) correct 0% (00:00) wrong based on 1 sessions

HideShow timer Statistics

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, is x/y an integer?

(1) every factor of y is also a factor of x
(2) every prime factor of y is also a prime factor of x

I have OA but cannot understand the explanation, was wondering if anyone could explain in different words?

Specifically, what confuses me is OA explanation's claim that if you test x/y = 18/8, it will satisfy criteria for (2). How can this be? As I see it:

Prime factors of 18 = (2)(3)(3)
Prime factors of 8 = (2)(2)(2)

Hence ONE prime factor of y is also a prime factor of x, but it's false that EVERY prime factor of y is also a prime factor of x. I would think you'd need three 2s, i.e. (2)(2)(2), i.e. 2^3 in x for this to be the case.

St1:
If every factor of y is also a factor of x, then x must be a multiple of y and so x/y = integer. Sufficient.

St2:
If x = 15 and it has primes 5,3 and y = 75 which has primes 5 and 3, then x/y = non-integer. However, if x = 15 and y = 5, then x/y = integer. INsufficient.