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

Redeem

Set question

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Senior | Next Rank: 100 Posts
Posts: 57
Joined: Thu Oct 08, 2009 12:02 am
Location: India

Set question

by mathewmithun » Wed Jun 20, 2012 1:31 am
I came accross this question while practicing:

S is a set of integers such that
i) if a is in S, then -a is in S, and
ii) if each of a and b is in S, then ab is in
S.
Is -4 in S?
(1) 1 is in S.
(2) 2 is in S.

OAA I went with C.
Trust in the Lord and do good,dwell in the land and live on it
Top
Source: — Data Sufficiency |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pm
Location: Milpitas, CA
Thanked: 1854 times
Followed by:523 members
GMAT Score:770

by Anurag@Gurome » Wed Jun 20, 2012 2:52 am
mathewmithun wrote:S is a set of integers such that
i) if a is in S, then -a is in S, and
ii) if each of a and b is in S, then ab is in S.
Is -4 in S?

(1) 1 is in S.
(2) 2 is in S.
Statement 1: As 1 is in S, -1 is also in S. But we cannot extend the logic from this point.

Not sufficient

Statement 2: As 2 is in S, -2 is also in S.
Now, 2 and -2 are in S.
Hence, (2)*(-2) = -4 is also in S.

Sufficient

The correct answer is B.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
Top
Senior | Next Rank: 100 Posts
Posts: 90
Joined: Wed Mar 21, 2012 1:27 am
Thanked: 5 times
Followed by:2 members

by sandeep_thaparianz » Wed Jun 20, 2012 2:53 am
If 2 is in set that means even -2 is in the set( rule 1)
Now that means 2*-2= -4 is also in set( rule 2)

You are sure that b is wrong???
Top
User avatar
Senior | Next Rank: 100 Posts
Posts: 57
Joined: Thu Oct 08, 2009 12:02 am
Location: India

by mathewmithun » Wed Jun 20, 2012 4:33 am
B it is, thanks Anurag and sandeep...
Trust in the Lord and do good,dwell in the land and live on it
Top
Post new topic Post Reply
• Page 1 of 1