probabilities. Please help

Question

consider the probability distribution shown. Find the u for this distribution.

X 2 4 9

p(x) 1/3 1/3 1/3

Answer 1

u = E(x) = Prob(2) * 2 + Prob(4) * 4 + Prob(9) * 9

= 1/3 * 2 + 1/3 * 4 + 1/3 * 9

= (1/3) ( 2 + 4 + 9)

= (1/3) (15) =

5