Callaway College (see Problem 11-35) would like to investigate the effect of adding the age of the student to the regression model. The table in Problem 11-35 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 1 l-35(c).