The following data show the advertising expenses (expressed as a percentage of total expenses) and the net operating profits (expressed as a percentage of total sales) in a random sample of six drugstores:
(a) Fit a least squares line that will enable us to predict net operating profits in terms of advertising expenses.
(b) Test the null hypothesis α = 0.8 against the alternative hypothesis α > 0.8 at the 0.01 level of significance.