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MBA.com practice test 2

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MBA.com practice test 2

by val1e » Thu Oct 21, 2010 11:28 am
If x=/= -y, is (x-y)/(x+y)>1


(1) x>0
(2) y<0

Apparently the answer is E, but how come?

The above inequation is equivalent to:

x - y > x + y

If you take the two statements together you get x>0 and y<0

Thus, if x is any positive number and y any negative number then x-y, as far as I can tell, will always be greater than x + y.
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by diebeatsthegmat » Thu Oct 21, 2010 6:41 pm
val1e wrote:If x=/= -y, is (x-y)/(x+y)>1


(1) x>0
(2) y<0

Apparently the answer is E, but how come?

The above inequation is equivalent to:

x - y > x + y

If you take the two statements together you get x>0 and y<0

Thus, if x is any positive number and y any negative number then x-y, as far as I can tell, will always be greater than x + y.
yep... the answer should be E
x# y and (x-y)/(x+y)>1 <=> (x-y)/(x+y)-1>0 <=> (x-y-x-y)/(x+y)=-2y/(x+y)>0
or 2y/(x+y)<0
1 and 2 both are not sufficient because with 1 we dont know y, with 2 we just dont know x
(1+2) x>0 and y<0
if x=2 and y=-1 : 2*-1/1=-1 <0 ( yes)
if x=2 y-3 : 2*-3/ -2=3 >0 ( no)
so insufficient
the correct answer is E
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by Testluv » Fri Oct 22, 2010 8:38 pm
Apparently the answer is E, but how come?

The above inequation is equivalent to:

x - y > x + y

If you take the two statements together you get x>0 and y<0

Thus, if x is any positive number and y any negative number then x-y, as far as I can tell, will always be greater than x + y.
Hi val1e,

Remember that in an inequality if we multiply or divide by a negative, the inequality sign flips.

Although in combination we know that x is pos and y is neg, we don't know their absolute values. So, (x+y) may be neg. So the inequality could also be:

x-y < x+y

In that case, do you still think the answer is C?...
Kaplan Teacher in Toronto
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