Atleast

Expert replies

gmatblood: Master | Next Rank: 500 Posts; Posts: 489; Joined: Tue Jul 05, 2011 11:10 amFollowed by: 5 members; Thanked: 28 times

by gmatblood » Fri Nov 04, 2011 10:53 am

If n is a positive integer,is the value of b-a at least twice the value of 3^n - 2^n
(1) a = 2^n+1 and b=3^n+1
(2) n =3

IMO: A

Like this post

Source: Beat The GMAT — Data Sufficiency | Fri Nov 04, 2011 10:53 am

neelgandham: Community Manager; Posts: 1060; Joined: Fri May 13, 2011 6:46 amFollowed by: 52 members; Location: Utrecht, The Netherlands; Thanked: 318 times

by neelgandham » Fri Nov 04, 2011 11:08 am

If n is a positive integer,is the value of b-a at least twice the value of 3^n - 2^n
(1) a = 2^n+1 and b=3^n+1 => b-a = 3^n-2^n, Sufficient
(2) n =3 Insufficient

IMO A

Anil Gandham
Welcome to BEATtheGMAT | Photography | Getting Started | BTG Community rules | MBA Watch
Check out GMAT Prep Now's online course at https://www.gmatprepnow.com/

Like this post

GMAT/MBA Expert

Anurag@Gurome: GMAT Instructor; Posts: 3835; Joined: Fri Apr 02, 2010 10:00 pmFollowed by: 523 members; Location: Milpitas, CA; Thanked: 1854 times; GMAT Score:770

by Anurag@Gurome » Fri Nov 04, 2011 10:55 pm

gmatblood wrote:If n is a positive integer,is the value of b-a at least twice the value of 3^n - 2^n
(1) a = 2^n+1 and b=3^n+1
(2) n =3

IMO: A

(1) a = 2^(n+1) and b = 3^(n+1) implies we have to find if 3^(n+1) - 2^(n+1) > 2*(3^n - 2^n)? or is 3 * 3^n - 2 * 2^n > 2 * 3^n - 2 * 2^n?
We get, 3*3^n > 2*3^n, which is clearly true. So, statement 1 is SUFFICIENT.

(2) n = 2 is clearly NOT sufficient to answer the question.

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/

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review