Suppose that a regional express delivery service company wants to estimate the cost of shipping a package (Y) as a function of cargo type, where cargo type includes the following possibilities: fragile, semi-fragile, and durable. Costs for 15 randomly chosen packages of approximately the same weight and same distance shipped, but of different cargo types, are provided in the file P14_16.xlsx.

a. Estimate a regression equation using the given sample data, and interpret the estimated regression coefficients.

b. According to the estimated regression equation, which cargo type is the most costly to ship? Which cargo type is the least costly to ship?

c. How well does the estimated equation fit the given sample data? How might the fit be improved?

d. Given the estimated regression equation, predict the cost of shipping a package with semi-fragile cargo.