For a Discrete Random Variable X, Which of the Following $\sum f \left( x _ { i } \right)$

Multiple Choice

For a discrete random variable X, which of the following computes the expected value?

A) $\sum f \left( x _ { i } \right)$
B) $\sum _ { i = 1 } ^ { \infty } x _ { i } f \left( x _ { i } \right)$
C) $\sum _ { i = 1 } ^ { \infty } x _ { i }$
D) $\sum ^ { f ( x ) }$