3

The number of hours devoted to studying a subject and the marks obtained by eight students in the corresponding examination is:

Hours (x)	20	16	34	23	27	32	18	22
Mark (y)	6.5	6	8.5	7	9	9.5	7.5	8

Calculate:

1 Line of regression of y on x.

2 The estimated mark a person would obtain who studied 28 hours.

x_i	y_i	x_i ·y_i	x_i²	y_i²
16	6	256	36	96
18	7.5	324	56.25	135
20	6.5	400	42.25	130
22	8	484	64	176
23	7	529	49	161
27	9	729	81	243
32	9.5	1,024	90.25	304
34	8.5	1,156	72.25	289
192	62	4,902	491	1,534