Chapter 9, Problem 56PS

The worldwide market share for the Mozilla Firefox web browser was $20.3\%$ in a recent month. (Data extracted from netmarketshare.com) Suppose that you decide to select a sample of 100 students at your university and you find that 25 use the Mozilla Firefox web browser.

a. Use the five-step p-value approach to try to determine whether there is evidence that the market share for the Mozilla Firefox web browser at your university is greater than the worldwide market share of $20.3\%$ . (Use the 0.05 level of significance.)

b. Suppose that the sample size is $n=400,$ and you find that $25\%$ of the sample of students at your university (100 out of 400) use the Mozilla Firefox web browser. Use the five-step p-value approach to try to determine whether there is evidence that the market share for the Mozilla Firefox web browser at your university is greater than the worldwide market share of $20.3\%$ . (Use the 0.05 level of significance.)

c. Discuss the effect that sample size has on hypothesis testing.

d. What do you think are your chances of rejecting any null hypothesis concerning a population proportion if a sample size of $n=20$ is used?