Question

1. Assume you have collected information from six students as to how many hours they work each week and their grade point averages (GPAs). The information is shown below. Calculate a and b in the regression equation (Y′ = bX + a). Show all working

(1)	(2)	(3)	(4)	(5)	(6)
Case	X	Y	ZX	ZY	ZX • ZY
1	10	3.80	-0.66	0.76	-0.50
2	20	3.44	0	0.14	0
3	40	2.50	1.32	-1.48	-1.95
4	35	2.81	0.99	-0.95	-0.94
5	0	4.00	-1.32	1.10	-1.45
6	15	3.62	-0.33	0.45	-0.15

Mean of X = 20                                  Standard Deviation of X = 15.17

Mean of Y = 3.36                               Standard Deviation of Y = 0.58

Note that the two variable, or number of hours worked each week (X) and GPA (Y), have been transformed into Z scores (see columns 4 and 5).

Answer 1