GMAT PREP Does z lie between x & y

This topic has expert replies
Source: — Data Sufficiency |

Senior | Next Rank: 100 Posts
Posts: 93
Joined: Tue Sep 02, 2008 5:34 pm
Thanked: 7 times

by hwiya320 » Sun Dec 07, 2008 5:52 pm
This problem sounds more trickier than it actually is...

OK, you have a number line and X is the center since we're looking for XY and XZ.

we don't know if x,y,z are positive or negative.

stmt 1) xyz <0 or xyz = negative.

We know that either one or all of them have to be negative value for it to be true.

for example,

if x = 1, y = 6, z = -3
1(6)(-3) = negative, so true. we also know that z is opposite direction of Y, so it does not lie on it.

but if all of them are negative..

x=-1, y=-6, z=-3, then the multiplied value is still negative, yet xz lies on xy.

so statement 1 is insufficient.

stmt II

xy = negative..

same, if y is -6, x = 1, z = 3, then 1 from -6 (distance of xy) = 7, which is greater than 1 to 3 (dist of xz).

but z can be -3, which lies on xy. so again, insufficient for statement II.

Together.

xyz = negative, xy = negative.

Then we know that x or y is going to be negative.

If y was negative, statement would answer that z is going opposite direction. but if X was -1, then y and z is going same direction, therefore insufficient.

so answer is E

Draw a line to help you understand this.

z x y
or
x z y

this is what the stem is asking.