I am having troubles with the following question, any help would be truly appreciated.
Thanks in advance
If a and b are integers and (ab)^5=96y, y could be?
A: 5
B: 9
C: 27
D: 81
E: 125
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
Problem Solving - Arithmetic question
This topic has expert replies
-
lucas211
- Senior | Next Rank: 100 Posts
- Posts: 97
- Joined: Mon Aug 04, 2014 5:39 pm
- Thanked: 1 times
- Followed by:2 members
Hello everybody
I am having troubles with the following question, any help would be truly appreciated.
Thanks in advance
If a and b are integers and (ab)^5=96y, y could be?
A: 5
B: 9
C: 27
D: 81
E: 125
I am having troubles with the following question, any help would be truly appreciated.
Thanks in advance
If a and b are integers and (ab)^5=96y, y could be?
A: 5
B: 9
C: 27
D: 81
E: 125
-
regor60
- Master | Next Rank: 500 Posts
- Posts: 415
- Joined: Thu Oct 15, 2009 11:52 am
- Thanked: 27 times
96y must be some number to the fifth power.lucas211 wrote:Hello everybody
I am having troubles with the following question, any help would be truly appreciated.
Thanks in advance
If a and b are integers and (ab)^5=96y, y could be?
A: 5
B: 9
C: 27
D: 81
E: 125
Factoring 96 into primes yields 2x2x2x2x2x3.
There are five 2's and one 3. In order to make this into a number to the fifth power four more 3's are needed.
3^4 is 81 and is provided by the "y"
-
Matt@VeritasPrep
- GMAT Instructor
- Posts: 2630
- Joined: Wed Sep 12, 2012 3:32 pm
- Location: East Bay all the way
- Thanked: 625 times
- Followed by:119 members
- GMAT Score:780
Another idea:
a�b� = 2�*3*y
Since the left side has TWO fifth powers, the right side should have TWO fifth powers. So we should have the right side be 2�3�. To do that, we need y = 3�, so y = 81 is a fine answer.
a�b� = 2�*3*y
Since the left side has TWO fifth powers, the right side should have TWO fifth powers. So we should have the right side be 2�3�. To do that, we need y = 3�, so y = 81 is a fine answer.
