Brand preference. In a small-scale experimental study of the relation between degree of brand liking (Y) and moisture content (XI) and sweetness (X2 ) of the product, the following results were obtained from the experiment based on a completely randomized design:

Yi	Xi1	Xi2
64	4	2
73	4	4
61	4	2
76	4	4
72	6	2
80	6	4
71	6	2
83	6	4
83	8	2
89	8	4
86	8	2
93	8	4
88	10	2
95	10	4
94	10	2
100	10	4

regression models (assume i =1 ...4):

\f\f