You found Set 2 has 0 SD, so thats comes last. Eliminate A,C,E
Between B and D; Notice numbers in set 1 are closer together and hence would have a smaller SD;
Order should be III,I,II D
SD
This topic has expert replies
Source: Beat The GMAT — Problem Solving |
-
shankar.ashwin
- Legendary Member
- Posts: 966
- Joined: Sat Jan 02, 2010 8:06 am
- Thanked: 230 times
- Followed by:21 members
-
neelgandham
- Community Manager
- Posts: 1060
- Joined: Fri May 13, 2011 6:46 am
- Location: Utrecht, The Netherlands
- Thanked: 318 times
- Followed by:52 members
I. 72, 73, 74, 75, 76
II. 74, 74, 74, 74, 74
III. 62, 74, 74, 74, 89
calculating the square of the numerator of the Standard deviation formula
(-2)^2 + (-1)^2 + 0^2 + 1^2 + 2^2 = 10
0^2 + 0^2 + 0^2 + 0^2 + 0^2 = 0
(-12)^2 + No need > 144
So III > I > II option D
II. 74, 74, 74, 74, 74
III. 62, 74, 74, 74, 89
calculating the square of the numerator of the Standard deviation formula
(-2)^2 + (-1)^2 + 0^2 + 1^2 + 2^2 = 10
0^2 + 0^2 + 0^2 + 0^2 + 0^2 = 0
(-12)^2 + No need > 144
So III > I > II option D
Anil Gandham
Welcome to BEATtheGMAT | Photography | Getting Started | BTG Community rules | MBA Watch
Check out GMAT Prep Now's online course at https://www.gmatprepnow.com/
Welcome to BEATtheGMAT | Photography | Getting Started | BTG Community rules | MBA Watch
Check out GMAT Prep Now's online course at https://www.gmatprepnow.com/
-
[email protected]
- Junior | Next Rank: 30 Posts
- Posts: 21
- Joined: Mon Oct 10, 2011 12:15 am
- Location: India
- Thanked: 4 times
- Followed by:1 members
Dear Shankar,
what you are saying in right but if we notice in option III middle numbers are same.
So if we say the IIIrd set has higher SD so all the deviations from mean should be same isnt it.
Please correct my understanding
what you are saying in right but if we notice in option III middle numbers are same.
So if we say the IIIrd set has higher SD so all the deviations from mean should be same isnt it.
Please correct my understanding
-
shankar.ashwin
- Legendary Member
- Posts: 966
- Joined: Sat Jan 02, 2010 8:06 am
- Thanked: 230 times
- Followed by:21 members
I am not sure I understand your question properly,
In set III, you have 5 elements of which 3 are equal (74) but the other two elements are quite far off from 74 (12 and 15 units away).
If you notice Set I, its 5 consecutive integers (each differ from the previous by 1)
Imagine plotting the points on a graph, SetI will have all its elements close together whereas SetIII would be scattered, the very definition of SD.
In this case, looking at the numbers we can say its SD would be more than the set with consecutive integers.
But if all the 3 sets had numbers close together, we would need the formula for SD (or) the way 'neelgandham' has posted. That is a foolproof way to do it, but if the numbers given are obvious such as this, I prefer to skip doing math and save time.
In set III, you have 5 elements of which 3 are equal (74) but the other two elements are quite far off from 74 (12 and 15 units away).
If you notice Set I, its 5 consecutive integers (each differ from the previous by 1)
Imagine plotting the points on a graph, SetI will have all its elements close together whereas SetIII would be scattered, the very definition of SD.
In this case, looking at the numbers we can say its SD would be more than the set with consecutive integers.
But if all the 3 sets had numbers close together, we would need the formula for SD (or) the way 'neelgandham' has posted. That is a foolproof way to do it, but if the numbers given are obvious such as this, I prefer to skip doing math and save time.
[email protected] wrote:Dear Shankar,
what you are saying in right but if we notice in option III middle numbers are same.
So if we say the IIIrd set has higher SD so all the deviations from mean should be same isnt it.
Please correct my understanding
-
[email protected]
- Junior | Next Rank: 30 Posts
- Posts: 21
- Joined: Mon Oct 10, 2011 12:15 am
- Location: India
- Thanked: 4 times
- Followed by:1 members
ok,
i got it now.
"neelgandham " can you please write the formula and its detail which you have used.
i got it now.
"neelgandham " can you please write the formula and its detail which you have used.
-
neelgandham
- Community Manager
- Posts: 1060
- Joined: Fri May 13, 2011 6:46 am
- Location: Utrecht, The Netherlands
- Thanked: 318 times
- Followed by:52 members
Hello Aksurana,[email protected] wrote:ok,
i got it now.
"neelgandham " can you please write the formula and its detail which you have used.
Please find below the attachment(Self explanatory)
- Attachments
-
Anil Gandham
Welcome to BEATtheGMAT | Photography | Getting Started | BTG Community rules | MBA Watch
Check out GMAT Prep Now's online course at https://www.gmatprepnow.com/
Welcome to BEATtheGMAT | Photography | Getting Started | BTG Community rules | MBA Watch
Check out GMAT Prep Now's online course at https://www.gmatprepnow.com/
GMAT/MBA Expert
-
Scott@TargetTestPrep
- GMAT Instructor
- Posts: 8087
- Joined: Sat Apr 25, 2015 10:56 am
- Location: Los Angeles, CA
- Thanked: 43 times
- Followed by:29 members
Recall that when comparing data sets with the same number of elements, the one with elements spreading out the most has the greatest standard deviation, and the one with elements closest to each other has the least standard deviation. Therefore, set III has the greatest standard deviation (because the elements are spread out the most), set II has the least standard deviation (because all the elements are the same) and set I will have a standard deviation between those of set III and set II.GmatKiss wrote: ↑Tue Nov 01, 2011 5:58 amI. 72, 73, 74, 75, 76
II. 74, 74, 74, 74, 74 - S.D = O??!!
III. 62, 74, 74, 74, 89
The data sets I, II, and III above are ordered from
greatest standard deviation to least standard deviation
in which of the following?
(A) I, II, III
(B) I, III, II
(C) II, III, I
(D) III, I, II
(E) III, II, I
Answer: D
Scott Woodbury-Stewart
Founder and CEO
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews
