gmat prep q

E IMO

It should be C

It is E.

But can you tell me why it is not C?


z or y can be in the ngeative area of the number line.
1 tells us that all together are positive. this means that two of them have to be negative or all three need to be positive

2 tells us that x and y are whether both pos or both negative...

if we combine 2 with one we should now that z lies on "other side" either way and is not between x and y ... this would mean answer C

Why am I wrong?

IMO the easiest way to approach number line problems is to draw all possible cases and use each of the cases as required for the statements independently and together(if needed).

Given: the distance between x and y is greater than the distance between x and z

Q: Is z between x and y

Case 1:

z -----x-------- y

Case 2:

y-------- x-- z

Case 3:

x--z---------y

Case 4:

y------z-------x


Stmt I

xyz < 0

Case 1(z-> neagtive x->positive y->positive) gives NO answer

Case 3 (x->negative z->positive y->positive) gives YES answer

INSUFF

Stmt II

xy < 0 (Either x is positive y negative or y is positive x is negative)

Case 2 gives us a NO answer

Case 3 gives us a YES answer

INSUFF


Stmt I and II together

Case 2 (y->negative x->positive z->positive) gives us a NO
Case 3 (x->negative z->positive y->positive) gives us a YES


INSUFF

Choose E)

I agree Cramya that the explanation is correct.
But that is time consuming.. for sure it will be atleast close to 2min..
Also in doing this approach, I am always worried whether I have forgotten a case/scenario ..

However, as of now, I dont have any other method.

A better way is to memorize the cases coz this type of question can easily occur.. as a 500-600 level q, and i would not want to spend too much time on this but still be accurate.

thanks

A better way is to memorize the cases coz

True !! but wat u mean by memorizing??? !!

i mean vittal, do u have a set of possibilities ! which is standard thru out ??

vishi

OOO I meant create a combination of 3 variables, another combination of 4 variables.
Now, as I am writing this reply, I realize that is impractical.

So I am thinking that we need to solve more problems of this type so that creating the different cases becomes second nature and easy.

I remember seeing a few problems of this type.


Let me think further and see whether I can come up with a cookie cutter solution.

Vittal,
I tried to draw it pretty(avoid the pretty dashes---- on the real gmat) .

Its the same as writing:

z x y
y x z

and then do the rest


Juts my opionion -> I would rather spend the 2 minutes to solve it to make sure I have covered all bases.

A better way is to memorize the cases coz this type of question can easily occur.. as a 500-600 level q, and i would not want to spend too much time on this but still be accurate

The only problem is the variables involved or their relationship will be different fro each problem so not sure if we can memorize a generic set of cases.

If there is an easier/generic approach, I am all for that.

Regards,
CR