Refer to Exercise 15-8 and the data file Browning.
a. Produce a regression equation that will predict the sales as a function of the other four variables.
b. Determine if the overall model is significant. Use a significance level of 0.05.
c. Conduct a test of hypothesis to discover if any of the independent variables are insignificant. Test using an alpha = 0.05.

Data from exercise 15.8

Paul Browning owns and operates a medium size company that sells sunglasses and beachwear to retailers in the United States and Canada. He is interested in analyzing the effect of several variables on the weekly sales for his business. He has collected data for a sample of 20 weeks, and the data are in a file called Browning.