In 2008, the online travel agency Travelocity reported that summer travelers booked their airline reservations an average of 73.3 days in advance. A random sample of 40 summer travelers in 2014 was selected, and the number of days travelers booked their airline reservations in advance was recorded. These data can be found in the Excel file titled Travelocity.xlsx.

a. Perform a hypothesis test using σ = 0.05 to determine if the average number of days reservations are booked in advance has changed since 2008.

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

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

d. Use PHStat to validate these results.