4-19. The following data give the starting salary for students who recently graduated from a local university and accepted jobs soon after graduation. The starting salary, grade-point average (GPA), and major (business or other} are provided. Other Suslnes Euslnes Other Euslnes (a) Using a computer, develop a regression model that could be used to predict starting salary based on GPA and major. (b) Use this model to predict the starting salary for a business major with a GPA of 3.0. (c) What does the model say about the starting salary for a business major compared to a nonbusiness major? (d) Do you believe this model is useful in predicting the starting salary? Justify your answer, using information provided in the computer output. Problem 4.20 (regression) *mllllons * 100,0005 Year Tourist Ridership 1 7 15 2 2 10 Bus and subway ridership in 3 6 13 Washington, DC, d uring the 4 4 15 summer months is believed to be 5 14 25 heavily tied to the number of 6 15 27 tourists visiting the city. During the 7 16 24 past twelve years. the following 3 12 20 data have been obtained. 9 14 27 10 20 44 1 1 15 34 12 7 17 (a) Plot the data and determine if a linear model is reasonable. (b) Develop a regression model. (c) What is the expected ridership if 10m people visit the city? (d) if there are no tourists at all, explain the predicted ridership