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Director
Joined: 08 Jun 2004
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x and y are positive integers, is X^y <= Y^x? 1. X = y^2 [#permalink]
 14 Aug 2006, 23:05
Question Stats:
0% (00:00) correct
 0% (00:00) wrong based on 0 sessions
x and y are positive integers, is X^y <= Y^x?
1. X = y^2
2. X = 2y
Not sure about the OA, let's discuss guys.
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CEO
Joined: 20 Nov 2005
Posts: 2934
Schools: Completed at SAID BUSINESS SCHOOL, OXFORD - Class of 2008
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I think this is A
St1:
x--------y-----------ANSWER
25------5-----------YES
1--------1----------YES
4--------2----------YES
SUFF
St2:
x--------y-----------ANSWER
8--------4----------YES
2--------1----------NO
1--------1-----------YES
INSUFF
_________________
SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008
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GMAT Instructor
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x and y are positive integers, is X^y <= Y^x?
1. X = y^2
2. X = 2y
With (1) LS= y^(2y) RS= y^(y^2)
If y=1, LS=RS=1, and if y is at least 2, y^2-2y=y(y-2)>=0, so y^2>=2y and RS>=LS
Suff
With (2) LS= (2y)^y RS= y^(2y)=(y^2)^y
Here if y=1 LS=2>1=RS, but if y=2, LS=RS=16
Not suff
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Manager
Joined: 12 May 2006
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I think this is A
Quote: St1:
x--------y-----------ANSWER
25------5-----------YES
1--------1----------YES
4--------2----------YES
SUFF
St2:
x--------y-----------ANSWER
8--------4----------YES
2--------1----------NO
1--------1-----------YES
INSUFF
_________________
I concur... A it is
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Manager
Joined: 20 Mar 2006
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Re: DS: X^y <= Y^x [#permalink]
17 Aug 2006, 21:17
M8 wrote: x and y are positive integers, is X^y <= Y^x?
1. X = y^2
2. X = 2y
Not sure about the OA, let's discuss guys.
x,y={I,+}
(1) x=4 y=2 Yes
x=1, y=1 yes
x=9, y = 3 yes
x=100, y =10 yes
AD
(2) x=2 y =1 No
x=4 y=2 Yes
Hence A
Heman
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Re: DS: X^y <= Y^x
[#permalink]
17 Aug 2006, 21:17
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