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

Redeem

Problem Solving

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 190
Joined: Thu Jan 14, 2010 8:29 pm
Thanked: 2 times

Problem Solving

by phoenix9801 » Thu May 31, 2012 8:21 pm
What is the average (arithmetic mean) weight of the p people in a certain group if the average weight of the p/3 heaviest people is 201 lbs and the average weight of the rest of the people in the group is 150 lbs?

A) 167
B) 160
C) 175.5
D) 186
E) 217
Top
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 520
Joined: Sat Apr 28, 2012 9:12 pm
Thanked: 339 times
Followed by:49 members
GMAT Score:770

by eagleeye » Thu May 31, 2012 8:30 pm
Easy way, let p=3, then 1 person is 201 and other 2 are 150 each.
Hence average =( 201+ 2*150)/3 = 501/3 = 167

Let me know if this helps :)
Top
Legendary Member
Posts: 1119
Joined: Fri May 07, 2010 8:50 am
Thanked: 29 times
Followed by:3 members

by diebeatsthegmat » Thu May 31, 2012 9:21 pm
eagleeye wrote:Easy way, let p=3, then 1 person is 201 and other 2 are 150 each.
Hence average =( 201+ 2*150)/3 = 501/3 = 167

Let me know if this helps :)
what if p=3 and 2 is 201 and 1 is 150??
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 385
Joined: Mon Apr 16, 2012 8:40 am
Location: Pune, India
Thanked: 186 times
Followed by:29 members

by aneesh.kg » Thu May 31, 2012 9:25 pm
diebeatsthegmat wrote: what if p=3 and 2 is 201 and 1 is 150??
Hi,

If 2 is 201 and 1 is 150, then you can calculate the Average in the same manner as eagleeye explained.

Average = (2*201 + 1*150)/3 = (2/3)*201 + (1/3)*150 = 184

This is called the concept of weighted mean.

(i) When the weight of 150 was higher, the Average (167) was closer to 150.
(ii) When the weight of 201 was higher, the Average (184) was closer to 201.
(iii) If the weight of 150 and 201 are equal, the average will be exactly in between them (175.5).
Aneesh Bangia
GMAT Math Coach
[email protected]

GMATPad:
Facebook Page: https://www.facebook.com/GMATPad
Top
Post new topic Post Reply
• Page 1 of 1