GMATPrep Q - std deviation

[smehmood]

How do we solve the attached q?
Thanks
M

[parallel_chase]

x,y,z SD=d

x+5,y+5,z+5, will have the same SD=d

if all the elements in a set are increased by the same number the SD remains the same.

You can try with numbers

2,4,6 will have the same SD as 7,9,11

[Stuart@KaplanGMAT]

x,y,z SD=d

x+5,y+5,z+5, will have the same SD=d

if all the elements in a set are increased by the same number the SD remains the same.

You can try with numbers

2,4,6 will have the same SD as 7,9,11

Correctamundo!

The only factors relevant to standard deviation is the number of terms and the spacing of the terms - the actual value of the terms is irrelevant.

So, if all we're doing is shifting all the terms in a set to the left or right, the SD will remain constant.

For example, any set of 3 consecutive even numbers will have the same SD.