GMAT prep

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GMAT prep

by ashishrs » Tue Jul 24, 2007 10:04 pm
If zy < xy < 0 is | x - z | + | x | = | z | ?

(1) z < x

(2) y > 0

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by chatekar » Tue Jul 24, 2007 10:27 pm
Statement [1]

Consider z= 2 and x =3,
then |x-z| + |x| = |3-2| + |3| = 1 + 3 = 4
and |z| = |2| = 2

Hence |x-z| + |x| is not equal to |z|

Consider another example

z = -4, x = -2
then |X-z| +|x| = | -2 + 4| + |-2| = 2 + 2 = 4
and |z| = |-4| = 4

Hence |x-z| + |x| = |z|

So statement [1] alone is not sufficient.

From statement [2]

as y > 0 and using zy < xy, we get z < x
And as proved earlier, this is not sufficient.

So statement [1] and [2] together are not sufficent.

Whats the OA?

Thanks

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by ashishrs » Wed Jul 25, 2007 12:14 am
OA is d...

For 2nd Statement : since y > 0 we can very well say that z < x < 0 hence ur example

z = -4, x = -2
then |X-z| +|x| = | -2 + 4| + |-2| = 2 + 2 = 4
and |z| = |-4| = 4

Hence |x-z| + |x| = |z|

tells that statement [2] is sufficient

For 1st condition : i feel to satisfy zy < xy < 0

y has to be greater than 0

hence condition same as specified in [2]

So [1] must also be sufficient

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by chatekar » Wed Jul 25, 2007 12:46 am
Hey

I forgot the last part of the expression..

Thanks