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absolute value DS

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Source: — Data Sufficiency |
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by blackarrow » Thu Apr 09, 2009 7:15 pm
My answer is A

x| > |y|?

is possible only when absolute value of X is greater than Absolute value of Y.(signs dont matter)

1. x^2 > y^2
This equation proves that x>y; even if x is negative as we are asked about absolutes
Sufficient

2. x > y
Insufficient. Lets try some values


1)Let x be 1 , y be -2. in this case x>y , however absolute terms answer is x<y

2) Let x be 2, y be 1, in this case x>y, however absolute terms answer is x>y
Insufficient


whats the OA
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by anshulseth » Fri Apr 10, 2009 12:33 am
The concepts of mod comes into play here:

The concept says:
If |X| > |Y|

then X > Y and -X < -Y

Use this to get the result as E.

You can try the mod concept by putting values.
So, lets take X =3, Y=2
So, 3>2, and -3<-2

Lets take negative values , X=-2, Y=-3
So, -2>-3 and 2<3

OR lets take X=3, Y=-1
3>-1 and -3<1
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Re: absolute value DS

by vittalgmat » Fri Apr 10, 2009 1:07 am
XeroShogun wrote:is |x| > |y|?

1. x^2 > y^2

2. x > y

Detailed explanations appreciated!

IMO A.

Stmt 1: x^2 > y^2.

take square root of stmt 1
ie sqrt(x^2) > sqrt(y^2)

==> |x| > |y| Sufficient.

Another method:

case 1: x = -5 , y = 3
(-5)^2 > (3^2)

so |x | > |y|

case 2: x = 5, y = 3
again |x| > |y|.


Stmt 2:
x > y

5 > 3 and |5| > |3| ==> Yes

5 > -6 but |5| < |-6| ===> NO
Not sufficient.

Hence ans is A
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by XeroShogun » Fri Apr 10, 2009 8:32 pm
Official Answer is A. I guess I should of posted that as well, but thanks for the explanations!
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