Question

To find standard deviation, take the square root of the independent variable. True or False

Answer 1

Answer: True

Solution:

The standard deviation (SD) is always equal to the square root of the variance.

σ =

Since the differences are squared, added and then rooted, negative standard deviations are not possible.

Suppose X and Y are independent random variables. Then, the variance of (X + Y) and the variance of (X - Y) are described by the following equations

Var(X + Y) = Var(X - Y) = Var(X) + Var(Y)

where Var(X + Y) is the variance of the sum of X and Y, Var(X - Y) is the variance of the difference between X and Y, Var(X) is the variance of X, and Var(Y) is the variance of Y.

SD(X + Y) =