The standard deviation of which of the following is equivalent to that of {m, r, p, n}?
A. 2m,2r,2p,2n
B. m+2,r+2,p+2,n+2
C. |m|,|r|,|p|,|n|
D. 1/m, 1/r, 1/p, 1/n
E. {m^2, r^2, p^2, n^2}
OA is B
I got this question, but i am not sure how to eliminate C. I plug in some values for m,r,p,n such as -8,-6,-4,-2. After calculating for C, I think it's SD is equivalent to {m, r, p, n}.
Kindly help.
Thanks
The standard deviation of which of the following is equivale
This topic has expert replies
- GMATGuruNY
- GMAT Instructor
- Posts: 15539
- Joined: Tue May 25, 2010 12:04 pm
- Location: New York, NY
- Thanked: 13060 times
- Followed by:1906 members
- GMAT Score:790
Original set:vinni.k wrote:The standard deviation of which of the following is equivalent to that of {m, r, p, n}?
C. |m|,|r|,|p|,|n|
i am not sure how to eliminate C. I plug in some values for m,r,p,n such as -8,-6,-4,-2. After calculating for C, I think it's SD is equivalent to {m, r, p, n}.
-1, -1, 1, 1.
Option C yields the following set:
1, 1, 1, 1.
The SD of the red set is 0, since the four values are all the same.
The SD of the blue set is NOT 0, since the four values are NOT all the same.
Eliminate C.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
- vinni.k
- Master | Next Rank: 500 Posts
- Posts: 421
- Joined: Sun Apr 17, 2011 4:27 am
- Location: India
- Thanked: 6 times
- Followed by:2 members
- GMAT Score:620
It is a good example. Now, i wonder why it didn't come to my mind.GMATGuruNY wrote: Original set:
-1, -1, 1, 1.
Option C yields the following set:
1, 1, 1, 1.
The SD of the red set is 0, since the four values are all the same.
The SD of the blue set is NOT 0, since the four values are NOT all the same.
Eliminate C.
Thanks Mitch. As always you are the best.
GMAT/MBA Expert
- Jeff@TargetTestPrep
- GMAT Instructor
- Posts: 1462
- Joined: Thu Apr 09, 2015 9:34 am
- Location: New York, NY
- Thanked: 39 times
- Followed by:22 members
We can adhere to the rule that when a constant is added to or subtracted from all the data points in a set, the standard deviation doesn't change.vinni.k wrote:The standard deviation of which of the following is equivalent to that of {m, r, p, n}?
A. 2m,2r,2p,2n
B. m+2,r+2,p+2,n+2
C. |m|,|r|,|p|,|n|
D. 1/m, 1/r, 1/p, 1/n
E. {m^2, r^2, p^2, n^2}
Thus, the standard deviation of m, r, p, n is the same as the standard deviation of m+2, r+2, p+2, n+2.
Answer:B
Jeffrey Miller
Head of GMAT Instruction
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews