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

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by BTGmoderatorLU » Sun Dec 27, 2020 8:20 am
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If d is the standard deviation x, y, and z, what is the standard deviation of x + 5, y + 5, z + 5?

A. d
B. 3d
C. 15d
D. d + 5
E. d + 15

The OA is A
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Re: If d is the standard deviation x, y, and z, what is the standard deviation of x + 5, y + 5, z + 5?

by Scott@TargetTestPrep » Sat Mar 20, 2021 1:23 pm
BTGmoderatorLU wrote: ↑
Sun Dec 27, 2020 8:20 am
 Source: GMAT Prep

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

A. d
B. 3d
C. 15d
D. d + 5
E. d + 15

The OA is A
Solution:

In a data set, if every number is increased (or decreased) by the same amount, the standard deviation of the data set will not be affected. That is, the new standard deviation is still equal to the original standard deviation. Here we see that each data value is increased by the same amount (5 in this case); therefore, the standard deviation will still be d.

Answer: A

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