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A Simple but confusing DS [ 8^a(1/4)^b = ? ]

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alive
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A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink] New post   17 Oct 2008, 01:43
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8^a(1/4)^b = ?

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

Lets see how you guys solve it :-D



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Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink] New post   17 Oct 2008, 02:08
8^a(1/4)^b = ?
2^3a 2^-2b = ?
so 2^(3a-2b) = ?

(S1) b = 1.5a

then 2^ (3a - 2(1.5a)) = ?
2^ (3a-3a) =?
2^0= 1......Suff

(S2) a = 2
2^(3(2) - 2b) =?
still stuck with b .....then ...insuff

my thought is A
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Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink] New post   17 Oct 2008, 02:23
You are right paeagain.. the OA is (A) :)

But whats confusing me, upon solving we end up with:

8^a.(1/4)^b

2^(3a).2^(-2b)

3a-2b = ?


But isn't it same as the S(1) itself:

b = 1.5a
2b = 3a

and if we further see our original equation 3a-2b = ?
it tells us 3a = 2b which is what the statement (1) is. So is it solving the question.
I know how you will explain this as 3a-2b= 0 so its sufficient but that is exactly the same as question stem.
:roll: :roll: :roll: :roll:
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Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink] New post   17 Oct 2008, 04:25
alive wrote:
You are right paeagain.. the OA is (A) :)

But whats confusing me, upon solving we end up with:

8^a.(1/4)^b

2^(3a).2^(-2b)

3a-2b = ?


But isn't it same as the S(1) itself:

b = 1.5a
2b = 3a

and if we further see our original equation 3a-2b = ?
it tells us 3a = 2b which is what the statement (1) is. So is it solving the question.
I know how you will explain this as 3a-2b= 0 so its sufficient but that is exactly the same as question stem.
:roll: :roll: :roll: :roll:


This is a C-Trap question. Search this forum for more details on C-Trap.

The question asks what is the value of 3a-2b.

Statement 1 says the value of 3a-2b is zero.

You will come across such questions .... like is x=0? and one of the statements will be like x^2 + y^2 = 0 which clearly says x=0. It may sound simple, but many people like me will fail to see the logic and fall for the C-Trap.
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Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink] New post   17 Oct 2008, 04:57
I don't know whether I would think about C-Traps etc., but
2^(3a -2b) = ?

from statement 1 :
3a = 2b
2^(2b-2b) = 2^0 = 1

from statement 2:
a= 2 - won't help
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Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink] New post   17 Oct 2008, 05:27
LiveStronger wrote:
I don't know whether I would think about C-Traps etc., but
2^(3a -2b) = ?

from statement 1 :
3a = 2b
2^(2b-2b) = 2^0 = 1

from statement 2:
a= 2 - won't help


Don't have to think about it :) Knowing doesn't hurt ....
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Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink] New post   17 Oct 2008, 06:37
Good one :-D

Btw, can you explain more about C- Traps ?
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Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink] New post   17 Oct 2008, 07:02
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LiveStronger wrote:
Good one :-D

Btw, can you explain more about C- Traps ?


Check this one first --- LONG ONE ---- viewtopic.php?t=34329



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Data Sufficiency (DS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
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Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink]
17 Oct 2008, 07:02
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