Question

The average age of online consumers ten 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 the appropriate hypotheses to be tested.

(b) The online shoppers in our sample consisted of 40 individuals, had an average age of 24.2

years, with a standard deviation of 5.3 years. What is the test statistic and p‐value for the

hypotheses being tested in part (a)? (Remark: Report the p‐value using the statistical table,

but NOT Excel function.)

(c) What is the practical implication of the conclusion of the hypothesis test at

1.         5% level of significance, and
2.         10% level of significance?

(d) Is our current sample large enough to estimate the mean age of online consumers to be

correct within ±1.5 years at 95% level of confidence? If not, how many additional individuals

need to be selected?

Answer 1