45. E-commerce, part 2. The average age of online consumers a few years ago was 23.3 years. As older individuals gain confidence with the Internet, it is believed that the average age has increased. We would like to test this belief.

a) Write appropriate hypotheses.

b) We plan to test the null hypothesis by selecting a random sample of 40 individuals who have made an online purchase during 2007. Do you think the necessary assumptions for inference are satisfied? Explain.

c) The online shoppers in our sample had an average age of 24.2 years, with a standard deviation of 5.3 years. What’s the P-value for this result?

d) Explain (in context) what this P-value means.

e) What’s your conclusion?