Last visit was: 16 Sep 2026, 10:18 It is currently 16 Sep 2026, 10:18
Decision Tracker
My Rewards
New comers' posts
New posts
Unanswered

Close

GRE Prep Club Daily Prep

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 GRE 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.

Go to My Error Log Learn more
Close

Request Expert Reply

Confirm Cancel
PREVIOUS TOPIC
NEXT TOPIC

GRE math Challenge #43-If N = 3^x*5^y, where x and y

Tags :
Find Similar Topics  About  Add a Tag

Show Tags
Hide Tags

User avatar
soumya1989
Director
Director
Joined: 16 May 2014
Posts: 590
Own Kudos [?]: 2215 [0]
Given Kudos: 0
GRE 1: Q165 V161
Send PM
GRE math Challenge #43-If N = 3^x*5^y, where x and y [#permalink] New post   28 Feb 2015, 03:27
Expert Reply
00:00

Question Stats:

100% (01:06) correct 0% (00:00) wrong based on 8 sessions

Hide Show timer Statistics

If \(N = 3^x*5^y\), where x and y are positive integers, and N has 12 positive factors, what is the value of N?

Column AColumn B
9 is not a factor125 is a factor


A. Only Column A is sufficient.
B. Only Column B is sufficient.
C. Column A and B both are needed
D. Column A and B both are insufficient
E. None of the columns are needed.
avatar
Kentuckycats19
Intern
Intern
Joined: 26 Mar 2015
Posts: 1
Own Kudos [?]: 0 [0]
Given Kudos: 0
Send PM
Re: GRE math Challenge #43 [#permalink] New post   26 Mar 2015, 16:31
That is not a GRE question, just FYI.

Posted from my mobile device Image
User avatar
soumya1989
Director
Director
Joined: 16 May 2014
Posts: 590
Own Kudos [?]: 2215 [0]
Given Kudos: 0
GRE 1: Q165 V161
Send PM
Re: GRE math Challenge #43 [#permalink] New post   31 Mar 2015, 09:10
Expert Reply
Yes you are right!
The idea is to solve maths problems regardless what exam it is. Just to challenge brains. :wink:
avatar
Peter
Manager
Manager
Joined: 27 Sep 2017
Posts: 110
Own Kudos [?]: 84 [0]
Given Kudos: 0
Send PM
Re: GRE math Challenge #43-If N = 3^x*5^y, where x and y [#permalink] New post   11 Mar 2018, 05:38
soumya1989 wrote:
If \(N = 3^x*5^y\), where x and y are positive integers, and N has 12 positive factors, what is the value of N?

Column AColumn B
9 is not a factor125 is a factor


A. Only Column A is sufficient.
B. Only Column B is sufficient.
C. Column A and B both are needed
D. Column A and B both are insufficient
E. None of the columns are needed.



For me, the ans would be A, we are told that \(N = 3^x*5^y\), where x and y are positive integers, and N has 12 positive factors.

then (x+1)(y+1)=12. Let us do some prime factorization of 12.

12=2*6=1*12=3*4 We should rule out the pair 1*12 since x+1 or y+1=1, then x or y=0. Yet, we are told that x and y are positive integers. Now for cloumn A, we are told that 9 is not a factor of N. This leads us to know x=1 and y=5. then \(N = 3^1*5^5\).

For column B, we are told that 125 is a factor. That means that y>=3. So, y would be 3 or 5. B can't help us decide the value of N.

ANS:A
Prep Club for GRE Bot
gmatclubot
Re: GRE math Challenge #43-If N = 3^x*5^y, where x and y [#permalink]
11 Mar 2018, 05:38
Moderators:
adewale223
GRE Instructor
166 posts
bronaugust
GRE Forum Moderator
37 posts
VibhuAnurag
GRE Instructor
275 posts
Nsp10
Moderator
45 posts
tyrant100
GRE Forum Moderator
144 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Main navigation

Partners

GRE Resources

www.ets.org/gre | About | Terms and Conditions and Privacy Policy | Prep Club for GRE Rules | Contact | Advertise