Find all School-related info fast with the new School-Specific MBA Forum

It is currently 22 Oct 2014, 22:10

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Standard deviation question

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 13 Jul 2009
Posts: 6
Followers: 0

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

Standard deviation question [#permalink] New post 17 Jul 2009, 15:24
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 100% (01:48) wrong based on 2 sessions
hi,

I got this below question as my first quant question in GMT prep 2. Please help me with the solution.

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

Answer choices -

1. 0 and 6
2. 0 and 12
3. 0 and 0
4. -6 and 0
5. 6 and 6

Thanks
Kaplan GMAT Prep Discount CodesKnewton GMAT Discount CodesVeritas Prep GMAT Discount Codes
1 KUDOS received
Manager
Manager
User avatar
Joined: 03 Jul 2009
Posts: 107
Location: Brazil
Followers: 3

Kudos [?]: 52 [1] , given: 13

Re: Standard deviation question [#permalink] New post 18 Jul 2009, 12:23
1
This post received
KUDOS
Standard deviation, by definition is a measure of the variability or dispersion of a population, a data set, or a probability distribution.

Once all the options have two numbers, each one of them, when added, will result in a list of 102 elements. So the point is how to make the standard deviation lower.

According to the definition if you add numbers farther then the average this makes the standard deviation grow. In the same way, the closer the new numbers are of the average, the lower will be the standard deviation.

Thus, E is the answer, since both values are equal to the average.
Manager
Manager
User avatar
Joined: 27 Jun 2008
Posts: 160
Followers: 2

Kudos [?]: 19 [0], given: 11

Re: Standard deviation question [#permalink] New post 22 Jul 2009, 00:09
Well explained coelholds, Imagine if d would have been provided should the number be equal to D in that case.
Intern
Intern
avatar
Joined: 24 May 2009
Posts: 38
Followers: 0

Kudos [?]: 16 [0], given: 4

Re: Standard deviation question [#permalink] New post 22 Jul 2009, 20:00
I did GMATPrep 2 yesterday, and faced this as the first question,too. I was really nervous and excited because I never imagined that a S.D. problem would come up the first one. However, GMAT always make us surprised.

Good explanation, coelholds. Thanks! :-D
Intern
Intern
avatar
Joined: 18 Aug 2009
Posts: 13
Followers: 1

Kudos [?]: 5 [0], given: 0

Re: Standard deviation question [#permalink] New post 05 Oct 2009, 05:28
Just curious - to switch this question around, which set of numbers, when added to the list, would result in the largest standard deviation from d?

Would it be 0 and 12?
Manager
Manager
avatar
Joined: 12 Oct 2009
Posts: 115
Followers: 2

Kudos [?]: 23 [0], given: 3

Re: Standard deviation question [#permalink] New post 14 Oct 2009, 13:46
ssy84 wrote:
Just curious - to switch this question around, which set of numbers, when added to the list, would result in the largest standard deviation from d?

Would it be 0 and 12?


now SD will be maximum if we have 2 numbers with maximum difference from avg. If we take 0 and 12 we get to add 2*6^2. But ifwe consider 0 and -6 we get to add 6^2 + 12^2 which will give the largest SD
Re: Standard deviation question   [#permalink] 14 Oct 2009, 13:46
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic Standard deviation question? fozzzy 5 16 Jan 2013, 23:42
Standard Deviation question mustu 7 07 Aug 2011, 13:04
Question about Standard Deviation jwegan 2 01 Nov 2010, 21:18
Experts publish their posts in the topic Questions about the standard deviation divakarbio7 18 01 Apr 2010, 22:19
Standard deviation question utsv 7 06 Jul 2006, 06:30
Display posts from previous: Sort by

Standard deviation question

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.