Question

What is the expected value of X?


X 3 4 5 7 9
P 0.2 0.1 0.25 0.05 0.4

6.2
6.05
5.95
5.6

Answer 1

Multiply each X by its corresponding probability P, then add up them up.

E[X] = 3•0.2 + 4•0.1 + 5•0.25 + 7•0.05 + 9•0.4

⇒   E[X] = 6.2