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# standard deviation

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08 Feb 2009, 01:10
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

if d is a standard deviation of x, y and z, what is the standard deviation of x+5, y+5 and z+5?
1) d
2) 3d
3) 15d
4) d+5
5) d+15

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Re: standard deviation [#permalink]

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08 Feb 2009, 07:03
1
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when each term in the series increases by the same amount,hence the mean also increase the same.The S.D does not change for the series.

Hence Ans : 1) d
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Re: standard deviation [#permalink]

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08 Feb 2009, 07:25
1
KUDOS
Zaur wrote:

if d is a standard deviation of x, y and z, what is the standard deviation of x+5, y+5 and z+5?
1) d
2) 3d
3) 15d
4) d+5
5) d+15

A

SD will not change if same number is added/sub from the given set of numbers...

Also, if the same number is multiplied/dvided from the given se of the number.. SD also have to be multiplied/dvided...
same case in percentage as well
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Re: standard deviation [#permalink]

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08 Feb 2009, 16:49
1
KUDOS
agree with A..

standard deviation will not change if you shift values by same number.
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Re: standard deviation [#permalink]

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08 Feb 2009, 16:56
1
KUDOS
Standard Deviation measures the difference between a set of numbers. If all the #'s are increased by the same amount (whether it's 5, 50, or 500) the standard deviation doesn't change.
So yes the answer is A.
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Re: standard deviation [#permalink]

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08 Feb 2009, 22:36
thanks a lot

brgds
Zaur
Re: standard deviation   [#permalink] 08 Feb 2009, 22:36
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# standard deviation

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