Recently, cell phone companies have been heavily investing in the African continent. With only half of its population owning a phone, Nigeria is considered a market that has much potential for growth. However, recent competition has driven prices for cell phones down in the country. It has been reported that the average monthly revenue earned per customer in Nigeria has been falling steadily since 2006 and is currently at $ 11. Vodafone, a U. K. cell phone company, has hired you to assist in the decision to enter the Nigerian market. If there is statistical evidence that the average monthly revenue is less than $ 11, Vodafone will choose not to invest in this market; otherwise, the company will invest. The Excel file labeled Nigeria.xlsx contains the monthly revenue from a random sample of 65 Nigerian mobile phone customers. Using PHStat with σ = 0.05, answer the following:

a. State the null and alternative hypotheses.

b. Based on this sample, what recommendations will you provide Vodafone?

c. Estimate the p value for this test using Table 5 in Appendix A.

d. Determine the precise p value for this test using Excel.

e. Use PHStat to validate these results.