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

 It is currently 28 Jun 2016, 20:52

### 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

# DS Standard Deviation

Author Message
Senior Manager
Joined: 20 Feb 2006
Posts: 373
Followers: 1

Kudos [?]: 15 [0], given: 0

### Show Tags

03 Dec 2006, 14:00
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.

Attachments

GMATQ6.xls [64 KiB]

Director
Joined: 28 Dec 2005
Posts: 921
Followers: 2

Kudos [?]: 43 [0], given: 0

### Show Tags

03 Dec 2006, 14:45
I get C:

From 1 and question S: (30+40+50+x+25)/5 = 40
=> x = 55

=> numbers are: 25,30,40,50,55

From 2: (30+40+50+p+45)/5 = 40

=> numbers are: 10,25,30,40,50

Together, this seems to imply T has the higher standard deviation. Either way, we dont need to know exactly, just the fact that we have all the numbers to do the calc is enough
Senior Manager
Joined: 08 Jun 2006
Posts: 340
Location: Washington DC
Followers: 1

Kudos [?]: 37 [0], given: 0

### Show Tags

03 Dec 2006, 14:51
C
From 1)
Set S - 25, 30, 40, 50, 55 (calculate the last one from average)
We know the SD of Set S but donâ€™t have any idea about the SD of T

From 2)
Set T - 30, 35, 40, 45, 50.

Together
30, 40 and 50 are common members. Other elements of these sets will decide which set has greater SD.
new elements of Set S are further away from the mean (40).
SD of Set S > SD of Set T
Senior Manager
Joined: 20 Feb 2006
Posts: 373
Followers: 1

Kudos [?]: 15 [0], given: 0

### Show Tags

03 Dec 2006, 15:43
OA is C - good work guys
Manager
Joined: 25 Nov 2006
Posts: 59
Followers: 2

Kudos [?]: 2 [0], given: 0

### Show Tags

03 Dec 2006, 18:13
Could you let me know the formula for Standard deviation??
Senior Manager
Joined: 23 May 2005
Posts: 266
Location: Sing/ HK
Followers: 1

Kudos [?]: 40 [0], given: 0

### Show Tags

04 Dec 2006, 10:10
get the mean
get the difference of the mean and each member of the set
square the differences
average the squared differences
take the square root of that average

i think GMAT rarely asks you to compute for SD. just tests the concept
_________________

Impossible is nothing

Senior Manager
Joined: 01 Oct 2006
Posts: 497
Followers: 1

Kudos [?]: 24 [0], given: 0

### Show Tags

05 Dec 2006, 13:23
For all SD questions you need to know terms in an individual series in order to be 100% sure.
Any information on mean median mode or range is not sufficient.

From st1 and given average we can determine ther terms in series one
From st2 and given average we can determie the terms in series 2

Individually 1 and 2 are not suff so eliminate A B and D

Comibing we find a solution so answer is C
Display posts from previous: Sort by