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# If d is the standard deviation of x, y, and z , what is the

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Director
Joined: 10 Feb 2006
Posts: 660

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If d is the standard deviation of x, y, and z , what is the [#permalink]

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20 Oct 2007, 09:59
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

If d is the standard deviation of x, y, and z , what is the standard deviation of x + 5, y + 5, z + 5.

d
3d
15d
d+5
d + 15

Ok, what would be the logic that when applied would give me the answer without going through the calculation. I know there is a simple rule that applies. here. Please help
Thanks
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Manager
Joined: 02 Aug 2007
Posts: 145

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20 Oct 2007, 10:06
2
KUDOS
You are correct, there is a rule here for solving quickly. When a constant is added to or subtracted from each element in the set, then the standard deviation does not change, however std dev will change with division or multiplication.

a. d

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Director
Joined: 11 Jun 2007
Posts: 910

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20 Oct 2007, 10:08
yuefei wrote:
You are correct, there is a rule here for solving quickly. When a constant is added to or subtracted from each element in the set, then the standard deviation does not change, however std dev will change with division or multiplication.

a. d

yup agreed with A) d

since we are adding a constant, the std dev does not change

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Manager
Joined: 07 Sep 2007
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20 Oct 2007, 10:08

because each number is increased by 5 the standard dev would not change.

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20 Oct 2007, 10:08
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