Question

The standard deviation of 10 observation is 15. If 5 is added to each observation the value of new standard deviation is

Answer 1

The answer is 15 since standard deviation is affected by multiplication or division and not addition or subtraction

Answer 2

The answer is 15.

GIVEN

Standard deviation of 10 = 15

TO FIND

If 5 is added to each observation the value of new standard deviation.

SOLUTION

The above problem can be simply solved as follows;

It is known that variance independent of the change of scale is;

V(X + a) = V(x)

Standard deviation of 10 observations = 15

Therefore, The standard deviation will remain the same.

Hence, The answer is 15.

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