Question

What is the mean of this discrete random variable? (That is, what is E(X), the expected value of X?)

A. 20
B. 18.59
C. 19
D. 19.625

Answer 1

Multiply each X by the corresponding probability P(X), then take the sum.

`E(X) = \displaystyle\sum_X XP(X) = 11\cdot0.07 + 14\cdot0.21 + \cdots + 29\cdot0.08 = \boxed{18.59}`

B