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Senior Manager
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If r and s are positive integers, is (r/s) an integer? [#permalink]
 22 Sep 2008, 12:03
Question Stats:
0% (00:00) correct
 0% (00:00) wrong based on 0 sessions
Is xy > x^2y^2?
(1) 14x^2 = 3
(2) y^2 = 1
Please show your workings
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SVP
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what the question is asking is whether 0<xy<1
From stmt1: x^2 = 3/14, hence x = sqrt(3/14), -sqrt(3/14).
From stmt2: y = 1, -1
Combining stmt1 and 2, xy = sqrt(3/14), -sqrt(3/14). Hence, not sufficient.
Hence, E.
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Senior Manager
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I was able to successfully solve this problem by plugging numbers. But, I'm looking to learn faster ways of solving such problems.
Could you please explain as to how you came to the conclusion that the question is essentially asking: 0<xy<1. Thanks
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Intern
Joined: 17 Sep 2008
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Schools: Chicago Booth, Wharton, MIT, Haas
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The inequality reduces to :
x^2y^2 - xy < 0
or xy(xy-1) < 0
This implies 0<xy<1
But instead of trying to derive this for the GMAT, you should probably remember that x^2<x implies 0<x<1
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CEO
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icandy wrote: Please underline SC questions.
Please Do not post OA along with the Q.
Give and take Kudos.
in addition to that, most importattly, mention the source of the question.
_________________
Verbal: new-to-the-verbal-forum-please-read-this-first-77546.html
Math: new-to-the-math-forum-please-read-this-first-77764.html
Gmat: everything-you-need-to-prepare-for-the-gmat-revised-77983.html
GT
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VP
Joined: 05 Jul 2008
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GMAT TIGER wrote: icandy wrote: Please underline SC questions.
Please Do not post OA along with the Q.
Give and take Kudos.
in addition to that, most importattly, mention the source of the question. If you were just making a point, thats fine. if you were thinking that I posted the Q, that was not me. I was annoyed with people posting OA along with Q and not underlining the SC Q. Thats how it came out.
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CEO
Joined: 29 Aug 2007
Posts: 2530
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icandy wrote: GMAT TIGER wrote: icandy wrote: Please underline SC questions.
Please Do not post OA along with the Q.
Give and take Kudos.
in addition to that, most importattly, mention the source of the question. If you were just making a point, thats fine. if you were thinking that I posted the Q, that was not me. I was annoyed with people posting OA along with Q and not underlining the SC Q. Thats how it came out. all your signature lines make sense. if you add "Always mention the source of the question" in your signature line, your signature lines would be a summary of gmat club forum etiquette. 
_________________
Verbal: new-to-the-verbal-forum-please-read-this-first-77546.html
Math: new-to-the-math-forum-please-read-this-first-77764.html
Gmat: everything-you-need-to-prepare-for-the-gmat-revised-77983.html
GT
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Senior Manager
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If we combine the 2 statements we have to prove that xy > 3/14.
Possible values of x are +/- (3/14)^1/2 and that of y are +/- 1
For all combinations of xy we get xy < 3/14
The ans is therefore C
Please correct me if I am wrong
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