mgmat ds 2 700-800

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mgmat ds 2 700-800

by pradeepkaushal9518 » Fri Sep 10, 2010 11:09 pm
Is x a negative number?

(1) x2 is a positive number.

(2) x × |y| is not a positive number.
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by anantbhatia » Sat Sep 11, 2010 12:06 am

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by pradeepkaushal9518 » Sat Sep 11, 2010 1:05 am
anant this is 700-800 level question.

can you explain yr answer?
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by anantbhatia » Sat Sep 11, 2010 1:29 am
I presume x2 actually is x^2

x^2 is positive means, x is either +ve or -ve. Hence, insufficient.

x.|y| means, x into a positive number. Since it is given that the product is negative, it means that x must be negative. Hence [spoiler](B)[/spoiler].

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by pradeepkaushal9518 » Sat Sep 11, 2010 2:02 am
what if x*/y/ is zero then both x and Y will be zero

i m posting OE

(1) INSUFFICIENT: Since x2 is positive whether x is negative or positive, we can only determine that x is not equal to zero; x could be either positive or negative.

(2) INSUFFICIENT: By telling us that the expression x × |y| is not a positive number, we know that it must either be negative or zero. If the expression is negative, x must be negative (|y| is never negative). However if the expression is zero, x or y could be zero.

(1) AND (2) INSUFFICIENT: We know from statement 1 that x cannot be zero, however, there are still two possibilites for x: x could be positive (y is zero), or x could be negative (y is anything).

The correct answer is E.
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by harupit200281 » Sat Sep 11, 2010 2:03 am
The answer should be C
St-1 clearly not enough
St-2 says x * |y| is not positive ==> means either the product is -ve or it is 0 so, not enough
combining both ... enough

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by anantbhatia » Sat Sep 11, 2010 2:49 am
pradeepkaushal9518 wrote:what if x*/y/ is zero then both x and Y will be zero



The correct answer is E.
Right!! Missed out the zero condition. Thanks