If X_i Is Defined as X_i = $\pi$ _i - E $\pi$

Multiple Choice

If x_i is defined as x_i = $\pi$ _i - E( $\pi$ _i) ,and p_i is the probability of occurrence of any x_i,the formula for the square of the standard deviation can be written as:

A) $\Sigma$ x_i p_i.
B) $\Sigma$ x_i p²_i .
C) $\Sigma$ x²_i p²_i .
D) $\Sigma$ x²_i p_i.
E) $\Sigma$ (x_i p_i) ².