Tricky DS

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Tricky DS

by gmatrant » Sat Nov 10, 2007 4:17 am
Is x a negative number?

(1) x2 is a positive number.

(2) x · |y| is not a positive number.

OA is E, but shouldn't the answer be C

[spoiler]From (1) I can conclude that x cannot be 0, but x can be -ve or +ve number.
From (2)I can conclude that x.|y| is either 0 or -ve number.
for this to be possible either x should be 0 or -ve number as irrespective of the value of y ; |y| is going to be positive.

Combining (1) and (2) we can say that x cannot be 0 , so x has to be negative.
[/spoiler]
Source: — Data Sufficiency |

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by samirpandeyit62 » Sat Nov 10, 2007 7:18 am
combine we can say that

x is either a -ve nos or a postive nos but not 0

& x.|y| is 0 or -ve

now for x.|y| = -ve x needs to be -ve

but for x.|y| = 0 , x can be 0 y can be 0 or both can be 0

in this case we acn consider a +ve value of x

coz if y =0 then x can be anything

so x can be -ve or +ve to satisfy the expr = 0

INSUFF E
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Samir

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by persevering » Sun Nov 11, 2007 12:56 pm
no (e) is good.
That stupid y could be zero.

Otherwise (C) would be OK.