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

Redeem

Set problem

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 79
Joined: Wed Feb 06, 2008 7:52 am
Thanked: 2 times
GMAT Score:620

Set problem

by yalanand » Sun Feb 01, 2009 12:11 am
S = {-20, -15, -5, 10, 10, 15, 40}. Which of the following are true?

I. The median of S is greater than the mean of S.
II. The standard deviation of S is greater than the range of S.
III. The range of S is twice the mode of S.

(A) I
(B) I and II
(C) I and III
(D) II and III
(E) III
Top
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 424
Joined: Sun Dec 07, 2008 5:15 pm
Location: Sydney
Thanked: 12 times

Re: Set problem

by piyush_nitt » Sun Feb 01, 2009 12:25 am
yalanand wrote:S = {-20, -15, -5, 10, 10, 15, 40}. Which of the following are true?

I. The median of S is greater than the mean of S.
II. The standard deviation of S is greater than the range of S.
III. The range of S is twice the mode of S.

(A) I
(B) I and II
(C) I and III
(D) II and III
(E) III
Median = 10
mean = 5
range = 40-(-20) = 60
mode = 10

1. median > mean - true
2. As mean = 5
range = 60
sd will be less than range. - false
3.false

IMO A
Top
Senior | Next Rank: 100 Posts
Posts: 79
Joined: Wed Feb 06, 2008 7:52 am
Thanked: 2 times
GMAT Score:620

by yalanand » Sun Feb 01, 2009 12:27 am
Well done...correct
Top
Master | Next Rank: 500 Posts
Posts: 158
Joined: Tue Sep 30, 2008 8:47 am
Thanked: 23 times
Followed by:1 members
GMAT Score:660

by DeepakR » Sun Feb 01, 2009 3:00 am
Can someone explain the Standard deviation step alone in #2 ?
Top
Senior | Next Rank: 100 Posts
Posts: 38
Joined: Tue Jan 27, 2009 10:24 am

by sanjay_dce » Sun Feb 01, 2009 5:54 am
DeepakR wrote:Can someone explain the Standard deviation step alone in #2 ?
S,D =(summ (xi-mean X)^2) ^1/2

I hope this helps it is also called root mean square of the deviations.

say if given values of x are 1,2,3,4,5

so obviously mean x = 3 ( i hope u already know this)
then x1-mean x = 1-3 = -2 , now square of -2 = 4
similarly x2-mean x = 2-3 = -1 now square of -1 = 1
and x3-meanx= 0 = 0

and all values are 1 and 4

now sum all these values = 1=4+0+1+4 = 10 and take square root of 10, ,, hence square root(10) is the std deviation of the given data set

-
Top
Post new topic Post Reply
• Page 1 of 1