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.

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 n and y are positive integers and 450y=n^3, which of the following must be an integer?

I. y / (3*4*5) II. y / (9*2*5) III. y / (3*2*25)

n^3 = 450 y
n^3 = 2 * 3^2 * 5^2 * y
Since n is an integer, the cube root of the right side of above equation should be an integer as well. The simplest way to make it an integer is if y = 2^2 * 3 * 5 = 60.

Now divide 60 by I II & III to see which work. Only I does so answer is A.

If n and y are positive integers and 450y=n^3, which of the following must be an integer?

I. y / (3*4*5) II. y / (9*2*5) III. y / (3*2*25)

n^3 = 450 y n^3 = 2 * 3^2 * 5^2 * y Since n is an integer, the cube root of the right side of above equation should be an integer as well. The simplest way to make it an integer is if y = 2^2 * 3 * 5 = 60.

Now divide 60 by I II & III to see which work. Only I does so answer is A.

i like this approach very much. thanks a lot for enlightening me