Set S contains seven distinct integers. The median of set S is the integer m, and all values in set S are equal to or less than 2m. What is the highest possible average (arithmetic mean) of all values in set S ?
m
10m/7
10m/7 - 9/7
5m/7 + 3/7
5m
OA:C
Please explain.I got it later,Distinct is the key word here
Please help with this CAT Problem
This topic has expert replies
- sanju09
- GMAT Instructor
- Posts: 3650
- Joined: Wed Jan 21, 2009 4:27 am
- Location: India
- Thanked: 267 times
- Followed by:80 members
- GMAT Score:760
@ skprocksskprocks wrote:Set S contains seven distinct integers. The median of set S is the integer m, and all values in set S are equal to or less than 2m. What is the highest possible average (arithmetic mean) of all values in set S ?
m
10m/7
10m/7 - 9/7
5m/7 + 3/7
5m
OA:C
In Order to maximize the individual members of the Set why can't we chose all values from first to fourth value as m and subsequently choose the rest as 2m.Please explain.
No, you can't take more than one value equal to m or 2 m, as the Set S contains seven distinct integers.
However, in order to maximize the average (arithmetic mean) of all values in set S, we must consider the integers being consecutive uptil m, with m being the fourth in counting order and the seventh integer being equal to or less than 2 m; why not take 7th equal to 2 m, and then downcount as 6th is 2 m - 1, and 5th is 2 m - 2.
Scene could look like: m - 3, m - 2, m - 1, m, 2 m - 2, 2 m - 1, 2 m
Hence, the highest possible average (arithmetic mean) of all values in set S
= 1/7 × (m - 3 + m - 2 + m - 1 + m + 2 m - 2 + 2 m - 1 + 2 m) = [spoiler]1/7 × (10 m - 9)
C[/spoiler]
The mind is everything. What you think you become. -Lord Buddha
Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001
www.manyagroup.com
Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001
www.manyagroup.com
- Gurpinder
- Legendary Member
- Posts: 659
- Joined: Mon Dec 14, 2009 8:12 am
- Thanked: 32 times
- Followed by:3 members
I know my approach probably wouldnt be the best one.....but it worked! So here it is:
Set S contains seven distinct integers. The median of set S is the integer m, and all values in set S are equal to or less than 2m. What is the highest possible average (arithmetic mean) of all values in set S ?
S {a,b,c,d,e,f,g}
d = median
g = 2d
SO I just came up with a set of values that would fit into these rules.
S = {0,1,2,3,4,5,6}
Median = 3
Highest value = 3x2=6
All other values are lower than 6
To get the mean, you just add up the values --> 21/7=3
The equation in option (C) gives me the same solution even if i plug in the value for M from the values i gave set S.
So (C).
Set S contains seven distinct integers. The median of set S is the integer m, and all values in set S are equal to or less than 2m. What is the highest possible average (arithmetic mean) of all values in set S ?
S {a,b,c,d,e,f,g}
d = median
g = 2d
SO I just came up with a set of values that would fit into these rules.
S = {0,1,2,3,4,5,6}
Median = 3
Highest value = 3x2=6
All other values are lower than 6
To get the mean, you just add up the values --> 21/7=3
The equation in option (C) gives me the same solution even if i plug in the value for M from the values i gave set S.
So (C).
"Do not confuse motion and progress. A rocking horse keeps moving but does not make any progress."
- Alfred A. Montapert, Philosopher.
- Alfred A. Montapert, Philosopher.
-
- Senior | Next Rank: 100 Posts
- Posts: 61
- Joined: Fri Feb 19, 2010 10:12 am
- Thanked: 3 times
Cool question..
So say the question is
median=mean=20
smallest number = (largest/2)-5
what is the largest number in this 7 number set ?
So say the question is
median=mean=20
smallest number = (largest/2)-5
what is the largest number in this 7 number set ?
-
- Legendary Member
- Posts: 1119
- Joined: Fri May 07, 2010 8:50 am
- Thanked: 29 times
- Followed by:3 members
supposed x1,x2,x3,x4,x5,x6,x7 are all 7 number we need to find, and all these numbers are differentskprocks wrote:Set S contains seven distinct integers. The median of set S is the integer m, and all values in set S are equal to or less than 2m. What is the highest possible average (arithmetic mean) of all values in set S ?
m
10m/7
10m/7 - 9/7
5m/7 + 3/7
5m
OA:C
Please explain.I got it later,Distinct is the key word here
x4= m and x1,x2, x3, x5,x6,x7<or =2m
to find the highest average value, suppose x7=2m and m<x6 and x5<2m, supposed em : 2m-1, 2m-2
and x1,x2,x3<m, supposed are m-3,m-2,m-1
added all this number together we get the answer C