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

Redeem

multiples of 3

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Data Sufficiency |
Legendary Member
Posts: 2789
Joined: Tue Jul 26, 2011 12:19 am
Location: Chennai, India
Thanked: 206 times
Followed by:43 members
GMAT Score:640

by GmatKiss » Wed Aug 10, 2011 8:42 am
IMO: D
Top
Legendary Member
Posts: 1448
Joined: Tue May 17, 2011 9:55 am
Location: India
Thanked: 375 times
Followed by:53 members

by Frankenstein » Wed Aug 10, 2011 8:46 am
finance wrote:Is positive integer n - 1 a multiple of 3?

(1) n3 - n is a multiple of 3

(2) n3 + 2n2+ n is a multiple of 3
Hi,
From(1):
n^3-n = n(n^2-1) = n(n-1)(n+1).
Product of three consecutive numbers is always a multiple of 3(in fact multiple of 6).
So, irrespective of the value of n, n3 - n is always a multiple of 3.
Not sufficient
From(2):
n(n+1)^2 is multiple of 3.
So, either n is multiple of 3 or (n+1) is multiple of 3.
So, (n-1) cannot be multiple of 3
Sufficient

Hence, B
Cheers!

Things are not what they appear to be... nor are they otherwise
Top
Legendary Member
Posts: 2789
Joined: Tue Jul 26, 2011 12:19 am
Location: Chennai, India
Thanked: 206 times
Followed by:43 members
GMAT Score:640

by GmatKiss » Wed Aug 10, 2011 8:49 am
I thought the question had,

1) (n.3 - n) is a multiple of 3
2) (n.3 + 2.n.2)+ n is a multiple of 3

:( :(
Top
Post new topic Post Reply
• Page 1 of 1