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

Redeem

What is the sum of the terms in a sequence of consecutive...

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Data Sufficiency |
User avatar
Legendary Member
Posts: 2663
Joined: Wed Jan 14, 2015 8:25 am
Location: Boston, MA
Thanked: 1153 times
Followed by:128 members
GMAT Score:770

by DavidG@VeritasPrep » Fri Nov 03, 2017 9:57 am
LUANDATO wrote:What is the sum of the terms in a sequence of consecutive multiples of 3?

(1) There is an odd number of terms in the sequence.

(2) The average of the sequence is zero.

The OA is B.

Please, can any expert explain this DS question? I need help to solve it. Thanks.
Statement 1: Clearly not sufficient.

Case 1: {3, 6, 9} --> sum. = 18
Case 2: {3, 6, 9, 12, 15} --> sum = 45

Statement 2: We know that Sum = Average * Number Terms.
If the Average = 0, then we have Sum = 0 * Number Terms = 0. So the Sum must be 0. We have a unique value. Sufficient. The answer is B
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course
Top
Post new topic Post Reply
• Page 1 of 1