Question

A college bookstore must order books two months before each semester starts. They believe that the number
of books that will ultimately be sold for any particular course is related to the number of students registered for
the course when the books are ordered. They would like to develop a linear regression equation to help plan
how many books to order. From past records, the bookstore obtains the number of students registered, X, and
the number of books actually sold for a course, Y, for 12 different semesters. These data are below.

Students Registered    Books Purchased
36 31
28 29
35 34
39 35
30 29
30 30
31 30

a. With these data, estimate and for a linear regression model. Explain, in complete sentences, what each
parameter estimate means.
b. Using your linear regression model, indicate how many books (rounded up to the near whole number)
should be ordered for a course with 40 registered students. In other words, use your model to estimate a
value when x=40.

Answer 1

	x	y	x^2	y^2	xy
	36	31	1296	961	1116
	28	29	784	841	812
	35	34	1225	1156	1190
	39	35	1521	1225	1365
	30	29	900	841	870
	30	30	900	900	900
	31	30	961	900	930
Total	229	218	7587	6824	7183