QNT/ 275-Two thousand randomly selected adults were asked whether

4. Two thousand randomly selected adults were asked whether or not they have ever shopped on the Internet. The following table gives a two-way classification of the responses.

Have Shopped

Have Never Shopped

Male

500

700

Female

300

500

a) If one adult is selected at random from these 2000 adults, find the probability that this adult has never shopped on the Internet.

b) If one adult is selected at random from these 2000 adults, find the probability that this adult is a male.

c) If one adult is selected at random from these 2000 adults, find the probability that this adult has shopped on the Internet given that this adult is a female.

If one adult is selected at random from these 2000 adults, find the probability that this adult is a male given that this adult has never shopped on the Internet.

7. The following table gives the probability distribution of a discrete random variable x.

x

0

1

2

3

4

5

6

P(x)

.11

.19

.28

.15

.12

.09

.06

Find the following probabilities.

a) P(1?x?4)

b) Probability that x assumes a value less than 4.

c) Probability that x assumes a value greater than 2.

9. Let xx be a discrete random variable that possesses a binomial distribution. Using the binomial formula, find the following probabilities.

a) p(5) for n=8 and p=.70

b) p(3) for n=4 and p=.40

Verify your answers by using Table I of Appendix B.

10. Let x be a discrete random variable that possesses a binomial distribution.

a) What is the mean (round to three decimal places)

b) What is the standard deviation of the probability distribution (round to three decimal places)?