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

Redeem

DS: average

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 55
Joined: Mon Jul 12, 2010 6:32 am

DS: average

by haidgmat » Sun Sep 05, 2010 5:45 pm
ok this seemed to be a very easy problem but I got it wrong. can someone please explain?

What is the average (arithmetic mean) height of the n people in a certain group?

1. The average height of the n/3 tallest people in the group is 6 feet 2 1/3 inches and the average height of the rest of the people in the group is 5 feet 10 inches

2. The sum of the heights of the n people is 178 feet 9 inches

Answer- A
Top
Source: — Data Sufficiency |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 1179
Joined: Sun Apr 11, 2010 9:07 pm
Location: Milpitas, CA
Thanked: 447 times
Followed by:88 members

by Rahul@gurome » Sun Sep 05, 2010 7:02 pm
(1) n/3 of certain group of people are 6 feet 2 1/3 inches tall.
Remaining people = 2n/3, so 2n/3 of people are 5 feet 10 inches tall.
So, Average height of n people = {(6 feet 2.3 inches)*(1/3) + (5 feet 10 inches)*(2/3)}, which can be calculated.

So, (1) is SUFFICIENT.

(2) Sum of the heights of n people cannot give us the average height of n people. So, (2) is NOT SUFFICIENT.

The correct answer is [spoiler](A)[/spoiler].
Rahul Lakhani
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
Top
Post new topic Post Reply
• Page 1 of 1