Chapter 6.4, Problem 13E

All of the following exercises can be done with a graphing calculator if your instructor so directs. The calculator can also be used to check your work.

Grade predictions. A professor wants to predict students’ final examination scores on the basis of their midterm test scores. An equation was determined on the basis of data consisting of the scores of three students who took the same course with the same instructor the previous semester (see the following table).

Midterm Score, x	Final Exam Score, y
70%	75%
60	62
85	89

a. Find the regression line, $y=mx+b$. (Hint: The y-deviation are $70m+b-75,$

$60m+b-62,$

and so on.)

b. The midterm score of a student was 81%. Use the regression line to the student’s final exam score.