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

Redeem

is √(x) < 2.5*(x - 5) ?

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
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 18, 2012 4:00 am
pappueshwar wrote:If x is a positive integer, is √(x) < 2.5 * (x - 5) ?

1) x < 3
2) x is a prime number

OA IS A. HOW TO DISPROVE STMNT 2
(1) x < 3 implies x can be either 1 or 2.
If x = 1 then √x = 1 and 2.5 * (x - 5) = 2.5 * (1 - 5) = 2.5 * -4 = -10. Here √(x) > 2.5 * (x - 5)
If x = 2 then √x = √2 and 2.5 * (x - 5) = 2.5 * (2 - 5) = 2.5 * -3 = -7.5. Here also √(x) > 2.5 * (x - 5)
So, √(x) > 2.5 * (x - 5); SUFFICIENT.

(2) x is a prime number.
If x = 2, then √x = √2 and 2.5 * (x - 5) = 2.5 * (2 - 5) = 2.5 * -3 = -7.5. Here √(x) > 2.5 * (x - 5)
If x = 7, then √x = √7 and 2.5 * (7 - 5) = 2.5 * (7 - 5) = 2.5 * 2 = 5. Here √(x) < 2.5 * (x - 5)
No definite answer; NOT sufficient.

The correct answer is A.
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
Post new topic Post Reply
• Page 1 of 1