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8^a*(1/4)^b = ?

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8^a*(1/4)^b = ? [#permalink]

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New post 04 Nov 2014, 09:31
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  35% (medium)

Question Stats:

64% (00:55) correct 36% (00:56) wrong based on 158 sessions

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Re: 8^a*(1/4)^b = ? [#permalink]

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New post 05 Nov 2014, 00:13
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We have: 8^a*(1/4)^b = 2^3a*2^(-2b) = 2^(3a - 2b)

S1:b = 1.5a --> 2b = 3a --> 3a - 2b = 0
--> 2^0 = 1
SUFF

S2: a = 2
NOT SUFF because we don't know b.

Ans:A
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Re: 8^a*(1/4)^b = ? [#permalink]

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New post 05 Nov 2014, 00:52
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Bunuel wrote:

Tough and Tricky questions: Exponents.



\(8^a*(\frac{1}{4})^b =\)?

(1) b = 1.5a
(2) a = 2

Kudos for a correct solution.



Question can written as 2^3a*(1/2^2)^b or 2^3a*2-2b...We need to find the value of 2^(3a-2b)

St 1 b=1.5a or 2b=3a so we have 2^0=1..Sufficient

St2 says a=2...but we don't know anything about b...in sufficient

Ans A
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Re: 8^a*(1/4)^b = ? [#permalink]

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New post 05 Nov 2014, 21:31
8^a*(1/4)^b = 2^(3a-2b)

Statement 1 : b = 1.5a => b = 3/2*a => 2b = 3a

Therefore 3a -2b = 0. Hence 2^(3a-2b) = 2^0 =1. Sufficient

Statement 2 : a = 2. It is clearly insufficient

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Re: 8^a*(1/4)^b = ? [#permalink]

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New post 16 Jan 2017, 17:56
Hello from the GMAT Club BumpBot!

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Re: 8^a*(1/4)^b = ? [#permalink]

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New post 08 Sep 2017, 21:26
Bunuel wrote:

Tough and Tricky questions: Exponents.



\(8^a*(\frac{1}{4})^b =\)?

(1) b = 1.5a
(2) a = 2

Kudos for a correct solution.


I personally think this is a 700 level question...classic "C" trap anyways

St 1

b =3/2 a

Just plug in a number

8^2 (1/4)^3 = 1 some reciprocal property

St 2

No info about B

Insuff

A

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Re: 8^a*(1/4)^b = ?   [#permalink] 08 Sep 2017, 21:26
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