It is currently 20 Nov 2017, 01:17

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

A certain list of 100 data has an average (arithmetic mean)

Author Message
Intern
Joined: 26 Feb 2008
Posts: 37

Kudos [?]: 7 [0], given: 0

A certain list of 100 data has an average (arithmetic mean) [#permalink]

Show Tags

22 Mar 2008, 17:17
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

A certain list of 100 data has an average (arithmetic mean) of 6 and a standard deviation of d, where d is positive. Which of the following pairs of data, when added to the list must result in a list of 102 data with standard deviation less than d?

(A) -6 & 0
(B) 0 & 0
(C) 0 & 6
(D) 0 & 12
(E) 6 & 6

Pls explain. Thanks.

Kudos [?]: 7 [0], given: 0

Senior Manager
Joined: 15 Aug 2007
Posts: 252

Kudos [?]: 72 [0], given: 0

Schools: Chicago Booth

Show Tags

22 Mar 2008, 19:02
E - Same question was posted a day ago. SD depends on the deviation from mean, so for values in E the deviations are zero which is the minimum we can get.

Kudos [?]: 72 [0], given: 0

SVP
Joined: 04 May 2006
Posts: 1878

Kudos [?]: 1443 [0], given: 1

Schools: CBS, Kellogg

Show Tags

22 Mar 2008, 19:59
sreehari wrote:
E - Same question was posted a day ago. SD depends on the deviation from mean, so for values in E the deviations are zero which is the minimum we can get.

Sorry guys, can you give more discription? Why "values in E the deviations are zero" make the new SD less than the old?
_________________

Kudos [?]: 1443 [0], given: 1

Manager
Joined: 02 Mar 2008
Posts: 205

Kudos [?]: 53 [0], given: 1

Concentration: Finance, Strategy

Show Tags

22 Mar 2008, 20:07
add 6 to the population of mean 6 does not change it mean
so the 2 new squares of difference are 0 -> reduce ur SD (divide by N+2)

Kudos [?]: 53 [0], given: 1

SVP
Joined: 04 May 2006
Posts: 1878

Kudos [?]: 1443 [0], given: 1

Schools: CBS, Kellogg

Show Tags

22 Mar 2008, 20:19
AlbertNTN wrote:
add 6 to the population of mean 6 does not change it mean
so the 2 new squares of difference are 0 -> reduce ur SD (divide by N+2)

Thank you,

I plan to make a stupid calculation.

_________________

Kudos [?]: 1443 [0], given: 1

Re: PS:Standard Deviation   [#permalink] 22 Mar 2008, 20:19
Display posts from previous: Sort by