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GMAT Club Legend
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Is xy > x/y ? 1) y = 1/3 2) x = 0 [#permalink]
 26 Aug 2004, 12:49
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Is xy > x/y ?
1) y = 1/3
2) x = 0
_________________
Best Regards,
Paul
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Intern
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A is not enough
becz if x=9 then 3<27 but if x is negetive then -3>-27
B is right i guess..
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Manager
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I think B is the answer too.
Although I am not sure, cause I think the answer is xy is not larger than x/y when x = 0.
y*0 = 0 and 0/y = 0
St.1 is not sufficient by using negatives and positives.
Correct me if I am wrong.
Regards,
Alex
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Director
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Paul wrote: Is xy > x/y ?
1) y = 1/3
2) x = 0
B
1 is not sufficient ... x can be anything
2 if x=0 then we have 0>0 which is not correct ~ sufficient
(assuming y<>0; i hope in gmat they frame the Qs clearly)
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GMAT Club Legend
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xy - x/y > 0
x(y - 1/y) > 0
From 1, if y = 1/3, then y - 1/y is negative. But we do not know if x is positive or negative.
If x is positive -> x(y - 1/y) < 0 . If x is negative, x(y - 1/y) > 0. So A is not sufficient.
From 2, if x = 0, then x(y-1/y) = 0. So we know x(y-1/y) is not greater than 0. Therefore B is sufficent.
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GMAT Club Legend
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Thanks everyone. I just wanted to confirm my doubt since OA given was E with some very dubious explanation. B should be it.
_________________
Best Regards,
Paul
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Manager
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I am leaning towards C.
My reasoning:
In statement(2), let y=0
then we have 0/0 (for x/y), which can be any real number (both -ve and +ve).
case 1: let 0/0 = -2
From (2) alone, 0>-2
case 2 : let 0/0 = 2
From (2) alone, 0<2
Hence satement (2) alone is not sufficient
Using (1) and (2)
xy>(x/y)?
0>0 ( which is not true)
So C looks like the answer
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Manager
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Paul,
Could you give us the very dubious explanation.
I am convinced that our answer B is correct, but I wonder why the OA is different.
Regards,
Alex
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GMAT Club Legend
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Alex_NL wrote: Paul,
Could you give us the very dubious explanation.
I am convinced that our answer B is correct, but I wonder why the OA is different.
Regards,
Alex
OE: From 1 alone, substituting y=1/3 we are comparing x/3 to 3x. But x/3 < 3x only if x is positive. Hence, we have choices B, C or E. 2 alone allows for the possibility that x=0, for which both sides are zero and thus equal; if x is not zero, the answer would depend upon the value of y. If we could say definitely that x is definitely either positive or negative, we could answer the question. However, x could be zero, and we cannot answer it. Hence, the best answer is choice E.
_________________
Best Regards,
Paul
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close
