Is x Negative?

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 179
Joined: Tue Jan 08, 2008 7:23 pm
Thanked: 11 times
GMAT Score:590

Is x Negative?

by nitya34 » Mon Mar 16, 2009 8:36 am
Is x a negative number?

statement 1: x^2 is a positive number
statement 2: x*lyl is not a positive number

I believe its not E its C
Source: — Data Sufficiency |

User avatar
Legendary Member
Posts: 682
Joined: Fri Jan 16, 2009 2:40 am
Thanked: 32 times
Followed by:1 members

Re: Is x Negative?

by Vemuri » Mon Mar 16, 2009 9:12 am
My answer is B.

The question is asking if x <0. We should look for statements that give a definite YES/NO answer.

Stmt 1: The answer we get is Yes & No. Since, there is no definite answer, this statement is insufficient.

Stmt 2: x*|y| < 0. Since |y| will always yield a positive number, x has to be -ve. This statement is sufficient to answer our main question.

Master | Next Rank: 500 Posts
Posts: 179
Joined: Tue Jan 08, 2008 7:23 pm
Thanked: 11 times
GMAT Score:590

Re: Is x Negative?

by nitya34 » Mon Mar 16, 2009 9:33 am
What about |y|=0? :)
Vemuri wrote:My answer is B.

The question is asking if x <0. We should look for statements that give a definite YES/NO answer.

Stmt 1: The answer we get is Yes & No. Since, there is no definite answer, this statement is insufficient.

Stmt 2: x*|y| < 0. Since |y| will always yield a positive number, x has to be -ve. This statement is sufficient to answer our main question.

User avatar
Master | Next Rank: 500 Posts
Posts: 316
Joined: Mon Sep 22, 2008 12:04 am
Thanked: 36 times
Followed by:1 members

Re: Is x Negative?

by Morgoth » Mon Mar 16, 2009 11:46 am
nitya34 wrote:Is x a negative number?

statement 1: x^2 is a positive number
statement 2: x*lyl is not a positive number

I believe its not E its C


x < 0 ?

Statement I

x^2 is a positive number

this means x is negative or positive but not 0.

insufficient.

Statement II

x*lyl is not a positive number

this means the above expression is either negative or 0

x could be negative or positive.

insufficient.


Combining I & II
x^2 is positive number
x*lyl is not a positive number

Case I

if x is negative & y is negative, x*lyl will always be negative since lyl will always be positive.

Case II

if x is positive & y = 0 x*lyl will be 0

Case III

if x is negative & y=0 x*lyl will be 0


Hence x could be negative or positive.

Insufficient.


Thus, E.

Hope this helps.

User avatar
Legendary Member
Posts: 682
Joined: Fri Jan 16, 2009 2:40 am
Thanked: 32 times
Followed by:1 members

Re: Is x Negative?

by Vemuri » Mon Mar 16, 2009 6:00 pm
nitya34 wrote:What about |y|=0? :)
[\quote]

Ooppss....thanks for correcting :lol:

Master | Next Rank: 500 Posts
Posts: 179
Joined: Tue Jan 08, 2008 7:23 pm
Thanked: 11 times
GMAT Score:590

by nitya34 » Mon Mar 16, 2009 9:11 pm
thanks Morgoth :)