Question

Value x of X
P (X=x)
-20
0.05
-10
0.55
0.0
0.10
10
0.05
20
0.25
Complete the following. (If necessary, consult a list of formulas.)
(a) Find the expectation E (X) of X.
E(x) =
(b) Find the variance Var(X) of X.