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DS ques-- gud 1

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by mental » Thu Oct 09, 2008 10:00 am
imo E
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by vivek.kapoor83 » Thu Oct 09, 2008 10:09 am
why E ?
and for checking the condition in ques we have to prove by considering that after removal of mod, it can be -ve and +ve
like
mod (x-y) > mod(x-z)

removing mod.
x-y > x-z
and -(x-y) > -(x-z)
do, we need to prove both the equation correct ? as after removing mod, you can have 2 values.(-ve & +ve) and mode for both will be same.
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by vivek.kapoor83 » Thu Oct 09, 2008 10:50 am
pls explain..this will clear the mod fn funda as well.
can any1 ans my ques.
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by mental » Thu Oct 09, 2008 11:02 am
Is mod (x-y) > mod(x-z)

a. mod y > mod z
b. x<0
It is a DS ques

a> it gives a relation in y and z, nothing about x..............insufficient
b> only tells us about x<0, nothing on y and z.................insufficient

together

we know x<0
lyl>lzl

lets take x=-10
y=-4, z=3
lx-yl>lx-zl...................
l-10-(-4)l = 6
l-10-3l=13....................6<13
so lx-yl<lx-zl

all same, just changing y, y=4
lx-yl=14......now 14>13
here lx-yl>lx-zl.........................insufficient

so IMO: E

whats OA?
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by vivek.kapoor83 » Thu Oct 09, 2008 11:26 am
OA is E. But u didnt reply the ques i askd above.
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by mental » Fri Oct 10, 2008 6:35 am
vivek.kapoor83 wrote:why E ?
and for checking the condition in ques we have to prove by considering that after removal of mod, it can be -ve and +ve
like
mod (x-y) > mod(x-z)

removing mod.
x-y > x-z
and -(x-y) > -(x-z)
do, we need to prove both the equation correct ? as after removing mod, you can have 2 values.(-ve & +ve) and mode for both will be same.
vivek, just a small thing was missed
when you remove mod it could be +ve or -ve, right

now we have an inequality here lx-yl > lx-zl
so it should result in four posiibilities
1. .......+(x-y) > +(x-z)........................both +ve
2. .......+(x-y) > -(x-z).........................lhs +ve, rhs -ve
3. .......-(x-y) > +(x-z).........................lhs -ve, rhs +ve
4. .......-(x-y) > -(x-z).........................both -ve


hope this helps
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by kris610 » Fri Oct 10, 2008 6:47 am
It's pretty simple:

Question asks the if the distance between X and Y is greater than the distance between X and Z.

A) tells you Y has a greater magnitude than Z. No info about X. Not suff.

B) tells you nothing about Y and Z. Obviously not sufficient.

A and B put together tell you Y could be negative or positive.

Y=-5 X=-2 and Z=3 satisfies both the conditions giving you a No as answer.

Y=5 X=-2 and Z=3 satisfies both the conditions giving you a YES.

So, E.
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