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Source: — Data Sufficiency |
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by raleigh » Sun May 31, 2009 8:09 pm
For quick reference, label (x-y)/(x+y) as (*).
(1) Choose x=1, y=-2. Then (*) = 3/-1 < 1
Now Choose x =10, y = -2. Then (*) = 12/8 > 1.

(1) is insufficient.

(2). Choose x = 1, y = -2. Then (*) = 3/-1 < 1
Choose x = 10, y = -2. Then (*) = 12/8 > 1

(2) is insufficient.

(1)+(2) Note that the same values made (1) and (2) insufficient. So apply those values to this case and you will get the same result. (1)+(2) is insufficient.

The answer is E.
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by aj5105 » Sun May 31, 2009 11:11 pm
How did you pick these values? Any quick method?

raleigh wrote:For quick reference, label (x-y)/(x+y) as (*).
(1) Choose x=1, y=-2. Then (*) = 3/-1 < 1
Now Choose x =10, y = -2. Then (*) = 12/8 > 1.

(1) is insufficient.

(2). Choose x = 1, y = -2. Then (*) = 3/-1 < 1
Choose x = 10, y = -2. Then (*) = 12/8 > 1

(2) is insufficient.

(1)+(2) Note that the same values made (1) and (2) insufficient. So apply those values to this case and you will get the same result. (1)+(2) is insufficient.

The answer is E.
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by aj5105 » Sun May 31, 2009 11:12 pm
How did you pick these values? Any quick method?

raleigh wrote:For quick reference, label (x-y)/(x+y) as (*).
(1) Choose x=1, y=-2. Then (*) = 3/-1 < 1
Now Choose x =10, y = -2. Then (*) = 12/8 > 1.

(1) is insufficient.

(2). Choose x = 1, y = -2. Then (*) = 3/-1 < 1
Choose x = 10, y = -2. Then (*) = 12/8 > 1

(2) is insufficient.

(1)+(2) Note that the same values made (1) and (2) insufficient. So apply those values to this case and you will get the same result. (1)+(2) is insufficient.

The answer is E.
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by raleigh » Mon Jun 01, 2009 8:37 am
I normally start by picking small numbers because they are easy to work with, ie 1 and 2.

x has to be positive and y has to be negative for x - y to have be greater than x + y (with y negative, the - will act as a +, and the + will act as a -).

So I pick something like x=1, y=-2 and get x-y=3, x+y=-1 < 1. Now I want to try to make the ratio greater than one. It was less than one because the denominator was negative. So how do we make it positive? Make x larger than y.

Try x=2, y=-1. Then x-y=3, and x+y=1 >1.
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Answer: E

by brick2009 » Mon Jun 01, 2009 9:45 pm
1.) 1 talks abt only X...Y is indeterminant..hence (1) insufficient..
2.) Same for 2...X value indeterminant...(2) insufficient...

Together...they yield multiple combinations of X and Y..hence...data is insufficient.
E
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