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 500,000 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 a and b are integers and (a*b)^5 = 96y, y could be: [#permalink]

Show Tags

23 Jan 2015, 19:58

1

This post received KUDOS

1

This post was BOOKMARKED

Bunuel wrote:

If a and b are integers and (a*b)^5 = 96y, y could be:

(A) 5 (B) 9 (C) 27 (D) 81 (E) 125

Kudos for a correct solution.

(a*b)^5 = 96y

96=(2^5)(3)

(a*b)^5 = (2^5)(3)(y) (a^5)*(b^5) = (2^5)(3)(y) y must be 3. to make both sides of the equation symmetrical, make y=(3^4) so that (a^5)*(b^5) = (2^5)(3^1)(3^4) (3^4) = 81

Re: If a and b are integers and (a*b)^5 = 96y, y could be: [#permalink]

Show Tags

09 Jul 2017, 05:26

1

This post was BOOKMARKED

Bunuel wrote:

If a and b are integers and (a*b)^5 = 96y, y could be:

(A) 5 (B) 9 (C) 27 (D) 81 (E) 125

Kudos for a correct solution.

\((a*b)^5 = 96y\)

\(a^5 * b^5 = 2^5 * 3^1 * y\)

As we can see that we are looking for the value \(3^5\) and we already have \(3\) so we would need \(3^4 = 81\)

\(a^5 * b^5 = 2^5 * 3^1 * 3^4\)

\(a^5 * b^5 = 2^5 * 3^5\)

\(y = 3^4 = 81\)

Hence, Answer is D _________________

"Nothing in this world can take the place of persistence. Talent will not: nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not: the world is full of educated derelicts. Persistence and determination alone are omnipotent."

Worried About IDIOMS?Here is a Daily Practice List: https://gmatclub.com/forum/idiom-s-ydmuley-s-daily-practice-list-250731.html#p1937393

Best AWA Template: https://gmatclub.com/forum/how-to-get-6-0-awa-my-guide-64327.html#p470475

Re: If a and b are integers and (a*b)^5 = 96y, y could be: [#permalink]

Show Tags

13 Nov 2017, 15:27

In this case is y the units digit of 96y or is it multiplying 96? I don't get it, because it states before that \(a*b\), with an "*". What is the pattern in GMAT? It will always state if it's the units digit when it's asking for the units digit?

If a and b are integers and (a*b)^5 = 96y, y could be: [#permalink]

Show Tags

13 Nov 2017, 15:42

guireif wrote:

In this case is y the units digit of 96y or is it multiplying 96? I don't get it, because it states before that \(a*b\), with an "*". What is the pattern in GMAT? It will always state if it's the units digit when it's asking for the units digit?

it doesn't matter, as everything under the parenthesis is raised to the power of 5. We apply PEMDAS - parenthesis/exponents/multiplication/division/addition/subtraction in this case, we can rewrite (a*b)^5 as (a)^5 * (b)^5 or (ab)^5. since prime factorization of 96 is 2^5 * 3, we can conclude that either a^5 or b^5 is 2^5, leaving us with the other equal to 3. since we have raised to the power of 5, but only one factor of 3 in the 96, it must be true that y is 3^4, or 81.

Re: If a and b are integers and (a*b)^5 = 96y, y could be: [#permalink]

Show Tags

13 Nov 2017, 15:53

mvictor wrote:

guireif wrote:

In this case is y the units digit of 96y or is it multiplying 96? I don't get it, because it states before that \(a*b\), with an "*". What is the pattern in GMAT? It will always state if it's the units digit when it's asking for the units digit?

it doesn't matter, as everything under the parenthesis is raised to the power of 5. We apply PEMDAS - parenthesis/exponents/multiplication/division/addition/subtraction in this case, we can rewrite (a*b)^5 as (a)^5 * (b)^5 or (ab)^5. since prime factorization of 96 is 2^5 * 3, we can conclude that either a^5 or b^5 is 2^5, leaving us with the other equal to 3. since we have raised to the power of 5, but only one factor of 3 in the 96, it must be true that y is 3^4, or 81.

Hi mvcitor, thanks but I think I wasn't clear enough. I'm asking if the question is asking "96*y" or "96y", which "y" is the units digit of the number "96y". And what would be the pattern in GMAT? Should I assume that 96y = 96*y?

In this case is y the units digit of 96y or is it multiplying 96? I don't get it, because it states before that \(a*b\), with an "*". What is the pattern in GMAT? It will always state if it's the units digit when it's asking for the units digit?

it doesn't matter, as everything under the parenthesis is raised to the power of 5. We apply PEMDAS - parenthesis/exponents/multiplication/division/addition/subtraction in this case, we can rewrite (a*b)^5 as (a)^5 * (b)^5 or (ab)^5. since prime factorization of 96 is 2^5 * 3, we can conclude that either a^5 or b^5 is 2^5, leaving us with the other equal to 3. since we have raised to the power of 5, but only one factor of 3 in the 96, it must be true that y is 3^4, or 81.

Hi mvcitor, thanks but I think I wasn't clear enough. I'm asking if the question is asking "96*y" or "96y", which "y" is the units digit of the number "96y". And what would be the pattern in GMAT? Should I assume that 96y = 96*y?

If 96y were a three-digit number it would have been mentioned explicitly. Without that, 96y can only be 96*y since only multiplication sign (*) is usually omitted.
_________________

If a and b are integers and (a*b)^5 = 96y, y could be: [#permalink]

Show Tags

14 Nov 2017, 04:17

Bunuel wrote:

guireif wrote:

In this case is y the units digit of 96y or is it multiplying 96? I don't get it, because it states before that \(a*b\), with an "*". What is the pattern in GMAT? It will always state if it's the units digit when it's asking for the units digit?

If 96y were a three-digit number it would have been mentioned explicitly. Without that, 96y can only be 96*y since only multiplication sign (*) is usually omitted.