If necessary consult a list of formulas Ex VarX Value of 10

(If necessary, consult a list of formulas.)

E(x)=

Var(X)=

Value of
-10	0.10
0	0.35
10	0.10
20	0.05
30	0.40

Solution

Consider this table:

x   P(x)   x P(x)   x^2 P(x)
-10   0.1   -1   10
0   0.35   0   0
10   0.1   1   10
20   0.05   1   20
30   0.4   12   360
Total       13   400

Thus,

E(x) = Sum( x P(x)) = 13 [answer]

Var(x) = E(x^2) - E(x)^2 = 400 - 13^2 = 231 [answer]