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: Is 30 a factor of n? [#permalink]
04 Jan 2013, 06:45

3

This post received KUDOS

Expert's post

2

This post was BOOKMARKED

daviesj wrote:

Is 30 a factor of n?

(1) 30 is a factor of the square of n (2) 30 is a factor of 2n

I doubt on OA...plz clarify

Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.

If n is not an integer, then the question does not make sense (at least for GMAT) .

The question should read: If n is an integer, is 30 a factor of n?

(1) 30 is a factor of n^2. If 30=2*3*5 is not a factor of n (if 2, 3 and 5 are not factors of n), then how this factors could appear in n^2? Exponentiation doesn't "produce" primes. Sufficient.

(2) 30 is a factor of 2n. Clearly insufficient: if n=15 then the answer is NO but if n=30 then the answer is YES. Not sufficient.

Re: Is 30 a factor of n? [#permalink]
04 Jan 2013, 07:01

1

This post received KUDOS

Expert's post

MacFauz wrote:

Bunuel wrote:

daviesj wrote:

Is 30 a factor of n?

(1) 30 is a factor of the square of n (2) 30 is a factor of 2n

I doubt on OA...plz clarify

Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.

If n is not an integer, then the question does not make sense (at least for GMAT) .

The question should read: If n is an integer, is 30 a factor of n?

(1) 30 is a factor of n^2. If 30=2*3*5 is not a factor of n (if 2, 3 and 5 are not factors of n), then how this factors could appear in n^2? Exponentiation doesn't "produce" primes. Sufficient.

(2) 30 is a factor of 2n. Clearly insufficient: if n=15 then the answer is NO but if n=30 then the answer is YES. Not sufficient.

Answer: A.

Hi Bunuel,

Just curious.. Why would the question not make sense if "n" were not an integer?

It does not make sense for GMAT since only integers can have factors. _________________

Re: Is 30 a factor of n? [#permalink]
04 Jan 2013, 06:43

daviesj wrote:

is 30 a factor of n? (1) 30 is a factor of the square of n (2) 30 is a factor of 2n

I doubt on OA...plz clarify

1) If n is \(\sqrt{30}\), Answer is no. If n is 30, answer is yes. Insufficient.

2)If n = 15, answer is no. If n = 30, answer is yes. Insufficient.

1 & 2 together. 2n has to be an even number to be divisible by 30. Hence, n has to be an integer. \(n^2\) is divisible by 30. So \(n^2\) should have at least one 2, one 3 and one 5. Since \(n^2\) is the square of an integer, this further implies that n^2 has to have at least two 2s, two 3s and two 5s. Hence n has at least one 2, one 3 and one 5. Hence divisible.

Answer is C _________________

Did you find this post helpful?... Please let me know through the Kudos button.

Re: Is 30 a factor of n? [#permalink]
04 Jan 2013, 06:51

Bunuel wrote:

daviesj wrote:

Is 30 a factor of n?

(1) 30 is a factor of the square of n (2) 30 is a factor of 2n

I doubt on OA...plz clarify

Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.

If n is not an integer, then the question does not make sense (at least for GMAT) .

The question should read: If n is an integer, is 30 a factor of n?

(1) 30 is a factor of n^2. If 30=2*3*5 is not a factor of n (if 2, 3 and 5 are not factors of n), then how this factors could appear in n^2? Exponentiation doesn't "produce" primes. Sufficient.

(2) 30 is a factor of 2n. Clearly insufficient: if n=15 then the answer is NO but if n=30 then the answer is YES. Not sufficient.

Answer: A.

Hi Bunuel,

Just curious.. Why would the question not make sense if "n" were not an integer? _________________

Did you find this post helpful?... Please let me know through the Kudos button.

Re: Is 30 a factor of n? [#permalink]
04 Jan 2013, 22:12

Bunuel wrote:

daviesj wrote:

Is 30 a factor of n?

(1) 30 is a factor of the square of n (2) 30 is a factor of 2n

I doubt on OA...plz clarify

Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.

If n is not an integer, then the question does not make sense (at least for GMAT) .

The question should read: If n is an integer, is 30 a factor of n?

(1) 30 is a factor of n^2. If 30=2*3*5 is not a factor of n (if 2, 3 and 5 are not factors of n), then how this factors could appear in n^2? Exponentiation doesn't "produce" primes. Sufficient.

(2) 30 is a factor of 2n. Clearly insufficient: if n=15 then the answer is NO but if n=30 then the answer is YES. Not sufficient.

Answer: A.

Bunnel- Is it not possible that for Statement 1:

If the number is 900 and 30 is a factor of 900, then it is possible that 30 (which is ) is a factor of the square root of 900. In the contrary, 60 is also a factor of 900 but is not a factor of the square root of 900.

Re: Is 30 a factor of n? [#permalink]
05 Jan 2013, 02:35

Expert's post

Drik wrote:

Bunuel wrote:

daviesj wrote:

Is 30 a factor of n?

(1) 30 is a factor of the square of n (2) 30 is a factor of 2n

I doubt on OA...plz clarify

Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.

If n is not an integer, then the question does not make sense (at least for GMAT) .

The question should read: If n is an integer, is 30 a factor of n?

(1) 30 is a factor of n^2. If 30=2*3*5 is not a factor of n (if 2, 3 and 5 are not factors of n), then how this factors could appear in n^2? Exponentiation doesn't "produce" primes. Sufficient.

(2) 30 is a factor of 2n. Clearly insufficient: if n=15 then the answer is NO but if n=30 then the answer is YES. Not sufficient.

Answer: A.

Bunnel- Is it not possible that for Statement 1:

If the number is 900 and 30 is a factor of 900, then it is possible that 30 (which is ) is a factor of the square root of 900. In the contrary, 60 is also a factor of 900 but is not a factor of the square root of 900.

Please shed some light.. Thanks

If prime number p is a factor of n^2 (where n is a positive integer), then p must be a factor of n.

So, the fact that 2, 3, and 5 are factors of n^2 means that 2, 3 and 5 must also be factors of n.

But if p^2 is a factor of n^2 (where n is a positive integer), then p^2 may or may not be a factor of n.

For example, if 60=2^2*3*5 is a factor of n^2, then all primes of 60 must also be factors of n, but 2^2 may or may not be a factor of n, so 60 may or may not be a factor of n.

Re: Is 30 a factor of n? [#permalink]
11 Nov 2014, 02:55

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. _________________

Type of Visa: You will be applying for a Non-Immigrant F-1 (Student) US Visa. Applying for a Visa: Create an account on: https://cgifederal.secure.force.com/?language=Englishcountry=India Complete...