If X and Y are independent random variables then the standard deviation of the random variable $X - Y$ is given by which of the following expressions?
A)SD(X)- SD(Y)
B) $\sqrt { \operatorname { Var } ( X ) + \operatorname { Var } ( Y ) }$
C) $\sqrt { \operatorname { Var } ( X ) - \operatorname { Var } ( Y ) }$
D)Var(X)+ Var(Y)
E)SD(X)+ SD(Y)

Question

Quizplus · Accepted Answer

The standard deviation of the difference of two independent random variables $X - Y$ is given by $\sqrt { \operatorname { Var } ( X ) + \operatorname { Var } ( Y ) }$, because the variance of the difference is the sum of the variances, and the standard deviation is the square root of the variance.

If X and Y Are Independent Random Variables Then the Standard