U. S. cell phone customers reportedly sent an average of 700 text messages per month in 2012, which is lower than previous years. Suppose AT& T would like to test the hypothesis that the average number of text messages per month has declined since 2012. A recent random sample of 75 U. S. cell phone users was selected and the number of text messages sent last month was recorded. These data can be found in the Excel file titled text messages. xlsx. Using σ = 0.05, answer the following:

a. State the null and alternative hypothesis.

b. Based on this sample, what conclusions can AT& T make about this population?

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.