=4-21 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.

Salary $29,500 $46,000 $39,800 $36,500 GPA 3.1 3.5 3.8 2.9 Major Other Business Business Other Salary $42,000 $31,500 $36,200 GPA 3.4 2.1 2.5 Major Business Other Business

(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.