A study performed in a large southern town to determine whether the average amount spent on food per four-person family in the town is significantly different from the national average. A random sample of 49 four-person families resulted in an average grocery bill of $159.33 with a standard deviation of $23.94. Assume the national average amount spent on food for a four person family is $155.

a. Identify the null and alternative hypothesis for this situation.

b. What is the p-value for the test? At what significance level can you reject the null hypothesis?

c. For which values of the sample mean (i.e., average weekly grocery bill) would you reject the null hypothesis at the 2% significance level? For which values of the sample mean would you reject the null hypothesis at the 8% level?