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

Redeem

median/average question

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 53
Joined: Thu Apr 12, 2007 12:32 am
Thanked: 1 times

median/average question

by jc114 » Wed Aug 20, 2008 9:57 pm
Set M has 15 numbers while Set K has 17 numbers. If one number from set K is taken and moved into set M, is the average of K larger than M?
(1) after moving a number into M, the median of M is smaller than the median of K.
(2) after moving a number into M, the average of M and the average of K both increased.

OA is B

Is there a better way to solve this than plugging #s??
Top
Source: — Data Sufficiency |
Legendary Member
Posts: 661
Joined: Tue Jul 08, 2008 12:58 pm
Location: France
Thanked: 48 times

by pepeprepa » Thu Aug 21, 2008 1:24 am
Why do you want to do something else than plugging?
I find it efficient here, you solve the question in a very few time.
Top
Senior | Next Rank: 100 Posts
Posts: 58
Joined: Fri Apr 04, 2008 12:36 pm
Thanked: 4 times
GMAT Score:680

Re: median/average question

by mim3 » Thu Aug 21, 2008 8:47 am
jc114 wrote:Set M has 15 numbers while Set K has 17 numbers. If one number from set K is taken and moved into set M, is the average of K larger than M?
(1) after moving a number into M, the median of M is smaller than the median of K.
(2) after moving a number into M, the average of M and the average of K both increased.

OA is B

Is there a better way to solve this than plugging #s??
You can plug in #'s but for me that would be really time consuming and I'd probably make a mistake along the way. Just by understanding how mean and median relate to each other, you can solve the problem without any calculation.

1. So we move a number from K to M and M's median is smaller than K's. I don't think this tells us much other than exactly what's stated. We don't know if K's was smaller before... we definitely don't know anything about the average. Insufficient

2. We move a number from K into M and both averages increase. From this we know that this number was below K's mean and above M's mean. So, K's mean is larger than M's. Sufficient.
Top
Senior | Next Rank: 100 Posts
Posts: 53
Joined: Thu Apr 12, 2007 12:32 am
Thanked: 1 times

by jc114 » Thu Aug 21, 2008 4:37 pm
I guess but who wants to plug in 15 and 17 #s?
I just want to understand the theory behind medians and averages..
Top
Post new topic Post Reply
• Page 1 of 1