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by vinay1983 » Fri Aug 30, 2013 3:01 am
[(8^2)(3^4)(2^4)]/(96^2)

(A) 3
(B) 6
(c) 9
(D) 12
(E) 18

OA is C

I chose C. This is how I did it.Where was I wrong?

64*81*16/96*96 yields 9 or [(2^6+4)*(3^4)]/(2^5)^2 * (3^2) yields 9
Last edited by vinay1983 on Fri Aug 30, 2013 6:32 am, edited 1 time in total.
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by Brent@GMATPrepNow » Fri Aug 30, 2013 5:49 am
vinay1983 wrote:[(8^2)(3^4)(2^4)]/(96^2)

(A) 3
(B) 6
(c) 9
(D) 12
(E) 18
Add some color: [(8^2)(3^4)(2^4)]/(96^2)

First, let's rewrite (96^2) so that it has terms that are similar to those in the numerator.

(96^2) = [(8)(12)]^2
= [(8)(3)(4)]^2
= [(8)(3)(2^2)]^2
= (8^2)(3^2)(2^4)

So, [(8^2)(3^4)(2^4)]/(96^2)
= [(8^2)(3^4)(2^4)]/(8^2)(3^2)(2^4)
= 3^2
= [spoiler]9 = C[/spoiler]

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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by vinay1983 » Fri Aug 30, 2013 6:13 am
Brent@GMATPrepNow wrote:
vinay1983 wrote:[(8^2)(3^4)(2^4)]/(96^2)

(A) 3
(B) 6
(c) 9
(D) 12
(E) 18
Add some color: [(8^2)(3^4)(2^4)]/(96^2)

First, let's rewrite (96^2) so that it has terms that are similar to those in the numerator.

(96^2) = [(8)(12)]^2
= [(8)(3)(4)]^2
= [(8)(3)(2^2)]^2
= (8^2)(3^2)(2^4)

So, [(8^2)(3^4)(2^4)]/(96^2)
= [(8^2)(3^4)(2^4)]/(8^2)(3^2)(2^4)
= 3^2
= [spoiler]9 = C[/spoiler]

Cheers,
Brent
Thanks Brent, will keep it in mind.

But the OA is A=3 not C=9!

What about it?
You can, for example never foretell what any one man will do, but you can say with precision what an average number will be up to!
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by Brent@GMATPrepNow » Fri Aug 30, 2013 6:19 am
vinay1983 wrote: But the OA is A=3 not C=9!
What about it?
Unless, you've transcribed the question incorrectly, the answer here is 9.
If the OA says otherwise, I'd have to say that the OA is incorrect :-)

Cheers,
Brent
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by vinay1983 » Fri Aug 30, 2013 6:32 am
Brent@GMATPrepNow wrote:
vinay1983 wrote: But the OA is A=3 not C=9!
What about it?
Unless, you've transcribed the question incorrectly, the answer here is 9.
If the OA says otherwise, I'd have to say that the OA is incorrect :-)

Cheers,
Brent
Sorry Brent.My bad!Edited OA!
Tell me is my method appropriate for solving such questions?

Thanks!
You can, for example never foretell what any one man will do, but you can say with precision what an average number will be up to!
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by Brent@GMATPrepNow » Fri Aug 30, 2013 7:09 am
vinay1983 wrote: Tell me is my method appropriate for solving such questions?
Yes, you're approach works perfectly.

You basically found the prime factorization of the numerator and denominator to get . . .
[(8^2)(3^4)(2^4)]/(96^2) = [(2^10)(3^4)]/[(2^10)(3^2)]
= 3^2

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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