Callaway College would like to investigate the effect of adding the age of the student to the regression model. The table in Problem 35 includes the ages of the original 12 students.
(a) Develop a multiple regression model to predict the GPA of a student based on his or her CBAT score and age.
(b) Identify and interpret the R2 value for this expanded regression model.
(c) The new student with a CBAT score of 630 is 29 years old. What is the revised 90% confidence interval for this student's predicted GPA? Explain why this interval is different from the one in Problem 35(c).