The human resources department at a firm developed a multiple regression to predict the success of candidates for available positions. Drawing records of new hires from five years ago, analysts regressed current annual salary on age at the time of hire and score on a test given to new hires. The path diagram below summarizes the fitted model. Age is coded in years, the test is scored from 1 to 20, and annual salary is in thousands of dollars ($m). Complete parts a through d. 7 points/ year Age 4 years/point Test Score 7 Sm/year Salary 4 Sm/point (a) Write down the equation for the multiple regression model. Est. Salary bo + 7 Age + 4 Test Score (b) Which is larger: the direct or indirect effect of test score? direct indirect (c) Find the marginal slope of salary on test score. marginal slope = 28 $m/point