Airlines were severely affected by the oil price increases of 2008. Even Southwest lost money, the first time ever, during that time. Many airlines began charging for services that had previously been free, such as baggage and meals. One national airline had as an objective of getting an additional $5 to $10 per trip from its customers. Surveys could be used to determine the success of the company’s actions. The file titled AirRevenue contains results of samples gathered before and after the company implemented its changes.
a. Produce a 95% confidence interval for the difference in the average fares paid by passengers before and after the change in policy. Based on the confidence interval, is it possible that revenue per passenger increased by at least $10? Explain your response.
b. Conduct a test of hypothesis to answer the question posed in part a. Use a significance level of 0.025.
c. Did you reach the same conclusion in both parts a and b? Is this a coincidence or will it always be so? Explain your response.