GMATPrep Test 1 #2_PS Number Properties #33

This topic has expert replies
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 » Sun Mar 11, 2012 9:19 pm
kwah wrote:What is the most efficient way to achieve the result for question attached?

Answer: B

Thanks,
K
M = finite set of negative integers, is the total number of integers in M an odd number?

(1) The product of all integers in M is odd.
If M = {-1, -1, -3), then product of integers in M = -3, which is odd and total number of integers in M = 3, an odd integer.
If M = {-1, -1, -1, -3), then product of integers in M = 3, which is odd and total number of integers in M = 4, an even integer.
No definite answer; NOT sufficient.

(2) Since the product of all integers in M is negative, so the total number of integers in M should always be odd because the product of even number of negatives always gives a postive number; 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/