Question

The p.m.f. of a random variable X is
`"P"(x) = 1/5` , for x = I, 2, 3, 4, 5 
        = 0 , otherwise.
Find E(X).

Answer 1

E(X) = `sum_(i = 1)^5  x."P"(x)`

= `1 xx 1/5 + 2 xx 1/5 xx 3 xx 1/5 + 4 xx 1/5 + 5 xx 1/5`

= `15/5`

= 3