*Consider the probability distribution

x P(x)

0 0.35

1 0.25

2 0.20

3 0.15

4 0.05

(a) Find the expected value.

(b) Find the standard deviation.

*Suppose that a large lot of electrical parts contains 9.5% defectives. A sample of 20 parts

is tested.

(a) what is the probability that exactly 2 were defective?

(b) what is the probability that more than one were defective?