BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

gmat prep q

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 109
Joined: Mon Sep 08, 2008 12:47 am

gmat prep q

by smallsorrow » Sat Sep 20, 2008 1:15 am
On the numberline, the distance between x and y is greater than the distance betweemn x and z. does z lie between and y on the number line?
1. xyz < 0
2. xy < 0

OA follows
Top
Source: — Data Sufficiency |
Senior | Next Rank: 100 Posts
Posts: 81
Joined: Thu Jun 12, 2008 1:57 pm
Thanked: 1 times

by nikhilagrawal » Sat Sep 20, 2008 3:34 am
E IMO
Top
Master | Next Rank: 500 Posts
Posts: 343
Joined: Mon Jan 21, 2008 3:28 pm
Thanked: 4 times

by arorag » Sat Sep 20, 2008 6:38 am
It should be C
Top
Master | Next Rank: 500 Posts
Posts: 109
Joined: Mon Sep 08, 2008 12:47 am

by smallsorrow » Sat Sep 20, 2008 9:06 am
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?
Top
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pm
Thanked: 331 times
Followed by:11 members

by cramya » Sat Dec 27, 2008 12:04 am
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)
Top
Legendary Member
Posts: 621
Joined: Wed Apr 09, 2008 7:13 pm
Thanked: 33 times
Followed by:4 members

by vittalgmat » Sat Dec 27, 2008 3:07 am
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
Top
Legendary Member
Posts: 574
Joined: Sun Jun 01, 2008 8:48 am
Location: Bangalore
Thanked: 28 times

by vishubn » Sat Dec 27, 2008 3:26 am
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
KILL !! DIE !! or BEAT my FEAR !!! de@D END!!
Top
Legendary Member
Posts: 621
Joined: Wed Apr 09, 2008 7:13 pm
Thanked: 33 times
Followed by:4 members

by vittalgmat » Sat Dec 27, 2008 4:00 am
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.
Top
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pm
Thanked: 331 times
Followed by:11 members

by cramya » Sat Dec 27, 2008 7:51 am
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
Top
Post new topic Post Reply
• Page 1 of 1