DataPro is a small but rapidly growing firm that provides electronic data-processing services to commercial firms, hospitals, and other organizations. For each of the past 12 months, DataPro has tracked the number of contracts sold, the average contract price, advertising expenditures, and personal selling expenditures. These data are provided in P10_17.xlsx. Using the number of contracts sold as the dependent variable; estimate a multiple regression equation with three explanatory variables. Interpret each of the estimated regression coefficients, the standard error of estimate, and R2.