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 350,000 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:

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]
02 Dec 2011, 20:21

1

This post received KUDOS

I'm a bit confused here. The question does not suggest that y is not 0. y = 0 satisfies both, y is divisible by 4 and y is divisible by 6. In that case we can say that y^3 is divisible by 9 and that D is the answer. Is it not correct?

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]
02 Dec 2011, 21:59

shm0401 wrote:

I'm a bit confused here. The question does not suggest that y is not 0. y = 0 satisfies both, y is divisible by 4 and y is divisible by 6. In that case we can say that y^3 is divisible by 9 and that D is the answer. Is it not correct?

You are right. The question should mention that Y cannot be 0 or that Y is a positive integer. If I read that question in the real test, I would assume that Y can be 0 too.

Kudos to you! _________________

"Life’s battle doesn’t always go to stronger or faster men; but sooner or later the man who wins is the one who thinks he can."

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]
03 Dec 2011, 16:41

Expert's post

metallicafan wrote:

shm0401 wrote:

I'm a bit confused here. The question does not suggest that y is not 0. y = 0 satisfies both, y is divisible by 4 and y is divisible by 6. In that case we can say that y^3 is divisible by 9 and that D is the answer. Is it not correct?

You are right. The question should mention that Y cannot be 0 or that Y is a positive integer. If I read that question in the real test, I would assume that Y can be 0 too.

Kudos to you!

While on the real GMAT, divisibility questions are always restricted to positive integers only, it doesn't actually make any difference to the answer here if you allow y to be zero. Statement 1 is still not sufficient (y might be 0 or 12, in which case y^3 is divisible by 9, or y might be 4 or 8, in which case y^3 is not divisible by 9), and Statement 2 is still sufficient, since y^3 must be divisible by 9 even if y=0 (since 0 is divisible by every positive integer). _________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]
04 Dec 2011, 03:04

The technique that Manhattan GMAT guides use make D-S questions easier. The key lies in paraphrasing the question and then paraphrasing the statements. It would be like this:

Question: What integer is y if (y^3)/9 = integer?

1) y is 4 or divisible by 4. y^3 = 4*4*4 = 64; 64/9 = 7.111 thus y is not an integer

2) y is 6 or divisible by 6. 6^3 = 6*6*6 = 216; 216/9 = 24 thus y is an integer

the correct answer is B.

There is also more accurate approach which could save you time if you know how to use it well. Since you know the value of y, you can use prime factorization to find the solution.

1) y is 4. prime factors are 2*2. y^3 = 2*2*2*2*2*2 the six twos are never divisible by 9, because prime factors of 9 are 3*3

2) y is 6. prime factors are 2*3. y^3 = 2*3*2*3*2*3 or 2^3*3^3. since y^3 has three 3's it must be divisible by two 3's

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]
04 Dec 2011, 20:56

for 1) try 12 - yes divisible, try 4- not divisible for 2) any number divisible by 6 is a multiple of 3, and 3^3 is 9 which is divisibe by 9. _________________

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]
05 Dec 2011, 04:34

I went with B because 6 has 2 and 3 as factors. so Y has 3 as a factor. therefore Y cube has at least 3 3s as a factor. So 9 which has only 2 3s can divide it

gmatclubot

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible
[#permalink]
05 Dec 2011, 04:34

On September 6, 2015, I started my MBA journey at London Business School. I took some pictures on my way from the airport to school, and uploaded them on...

When I was growing up, I read a story about a piccolo player. A master orchestra conductor came to town and he decided to practice with the largest orchestra...

Amy Cuddy, Harvard Business School professor, at TED Not all leadership looks the same; there is no prescribed formula for what makes a good leader. Rudi Gassner believed that...

We are thrilled to welcome the Class of 2017 to campus today, and data from the incoming class of students indicates that Kellogg’s community is about to reach a...