cx > cy ?

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cx > cy ?

by islands80 » Thu May 17, 2012 6:27 pm
If x > y, is cx > cy ?

(1) c > 0
(2) xy > 0

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by Anurag@Gurome » Thu May 17, 2012 6:35 pm
islands80 wrote:If x > y, is cx > cy ?

(1) c > 0
(2) xy > 0
(1) c > 0 and x > y implies cx > cy; SUFFICIENT.

(2) xy > 0 implies either both x and y are negative or both x and y are positive.
If x = -2, y = -3, c = 1, then cx = -2, cy = -3 implies cx > cy
If x = 2, y = 1, c = -1, then cx = -2, cy = -1 implies cx < cy
No definite answer; NOT sufficient.

The correct answer is A.
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by mathbyvemuri » Thu May 17, 2012 6:38 pm
Answer "A"
If x>y, irrespective of signs of x and y, if a positive value 'c' is multiplied on both sides, there won't be any change in the inequality.
=> cx>cy, if c>0 Statement-A alone is sufficient.
Statement B says xy>0 => Either both x and y are positive or both are negative. This clue won't be effective. Only the nature of 'c' influences here.