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# A set of data consists of the following 5 numbers: 0,2,4,6,

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VP
Joined: 22 Nov 2007
Posts: 1080
A set of data consists of the following 5 numbers: 0,2,4,6, [#permalink]

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02 Mar 2008, 00:19
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

A set of data consists of the following 5 numbers: 0,2,4,6, and 8. Which two
numbers, if added to create a set of 7 numbers, will result in a new standard
deviation that is closest to the standard deviation for of the 5 original numbers?

-1 and 9
4 and 4
3 and 5
2 and 6
0 and 8
SVP
Joined: 29 Aug 2007
Posts: 2473

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02 Mar 2008, 01:19
marcodonzelli wrote:
A set of data consists of the following 5 numbers: 0,2,4,6, and 8. Which two numbers, if added to create a set of 7 numbers, will result in a new standard deviation that is closest to the standard deviation for of the 5 original numbers?

-1 and 9
4 and 4
3 and 5
2 and 6
0 and 8

C. 4 and 4

since mean is 4, adding 4 and wont change the mean and consequently deviation.
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VP
Joined: 22 Nov 2007
Posts: 1080

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03 Mar 2008, 12:14
GMAT TIGER wrote:
marcodonzelli wrote:
A set of data consists of the following 5 numbers: 0,2,4,6, and 8. Which two numbers, if added to create a set of 7 numbers, will result in a new standard deviation that is closest to the standard deviation for of the 5 original numbers?

-1 and 9
4 and 4
3 and 5
2 and 6
0 and 8

C. 4 and 4

since mean is 4, adding 4 and wont change the mean and consequently deviation.

wrong. we need to reason following a standard deviation logic, not a mean logic. therefore, as long as mean is 4, the addition of 2 elements which are still 2 units from the mean won't affect D strongly
Re: stats   [#permalink] 03 Mar 2008, 12:14
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