Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 06 May 2015, 06:04

### GMAT Club Daily Prep

#### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

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

Author Message
TAGS:
Intern
Joined: 09 Oct 2008
Posts: 19
Followers: 0

Kudos [?]: 2 [0], given: 0

A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink]  17 Oct 2008, 00:43
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
8^a(1/4)^b = ?

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

Lets see how you guys solve it
Intern
Joined: 24 Jun 2007
Posts: 30
Followers: 1

Kudos [?]: 1 [0], given: 0

Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink]  17 Oct 2008, 01:08
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
Intern
Joined: 09 Oct 2008
Posts: 19
Followers: 0

Kudos [?]: 2 [0], given: 0

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.
VP
Joined: 30 Jun 2008
Posts: 1048
Followers: 11

Kudos [?]: 348 [0], given: 1

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.

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.
_________________

"You have to find it. No one else can find it for you." - Bjorn Borg

Senior Manager
Joined: 21 Apr 2008
Posts: 270
Location: Motortown
Followers: 1

Kudos [?]: 99 [0], given: 0

Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink]  17 Oct 2008, 03:57
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
VP
Joined: 30 Jun 2008
Posts: 1048
Followers: 11

Kudos [?]: 348 [0], given: 1

Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink]  17 Oct 2008, 04:27
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 ....
_________________

"You have to find it. No one else can find it for you." - Bjorn Borg

Senior Manager
Joined: 21 Apr 2008
Posts: 270
Location: Motortown
Followers: 1

Kudos [?]: 99 [0], given: 0

Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink]  17 Oct 2008, 05:37
Good one

Btw, can you explain more about C- Traps ?
VP
Joined: 30 Jun 2008
Posts: 1048
Followers: 11

Kudos [?]: 348 [1] , given: 1

Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ] [#permalink]  17 Oct 2008, 06:02
1
KUDOS
LiveStronger wrote:
Good one

Btw, can you explain more about C- Traps ?

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

"You have to find it. No one else can find it for you." - Bjorn Borg

Re: A Simple but confusing DS [ 8^a(1/4)^b = ? ]   [#permalink] 17 Oct 2008, 06:02
Similar topics Replies Last post
Similar
Topics:
If the perimeter of rectangle Q - Confused about simple Q 3 19 Nov 2011, 12:28
DS - Word problem [confusing] 12 01 Sep 2009, 22:57
PS simple but confusing square root 4 01 Feb 2009, 20:09
Simple but confused... Researchers have questioned the use 3 21 Sep 2008, 05:44
DS: Confusing question 1 02 Sep 2006, 18:56
Display posts from previous: Sort by