If necessary consult a list of formulas Value of 4 010 5 015

(If necessary, consult a list of formulas.)

Value of
4	0.10
5	0.15
6	0.05
7	0.30
8	0.25
9	0.15

Solution

Using this table,

x   P(x)   x P(x)   x^2 P(x)
4   0.1   0.4   1.6
5   0.15   0.75   3.75
6   0.05   0.3   1.8
7   0.3   2.1   14.7
8   0.25   2   16
9   0.15   1.35   12.15
          
Total       6.9   50

And that

E(x) = Sum(xP(x)),

E(x) = 6.9 [answer]
************

Var(x) = E(x^2) - E(X)^2

As E(x^2) = 50,

Var(x) = 50 - 6.9^2 = 2.39 [ANSWER]