A study is performed in large southern town to find whether the average weekly grocery bill per four-person family in town is significantly different from national average. A random sample of the weekly grocery bills of four-person families in this town is given in the Problem 3 worksheet of the Homework 8.xlsx spreadsheet in the Data Sets folder of the course webpage.
a. Suppose that the national average weekly grocery bill for a four-person family is $100. Using the p-value approach, what would you conclude?
b. For which values of the sample mean (i.e., average weekly grocery bill) would you reject the null hypothesis at the 1% significance level? For which values of the sample mean would you reject the null hypothesis at the 10% level?