Exercise 9.5 An experiment was conducted with two treatments. There were four levels of the first treatment and five levels of the second treatment. Besides the data y, two covariates were measured, x1 and x2. The data are given below. Analyze the data with the assumption that there is no interaction between the treatments.

i j yi j x1i j x2i j i j yi j x1i j x2i j 1 1 27.8 5.3 9 3 1 22.4 3.0 13 2 27.8 5.2 11 2 21.0 4.5 12 3 26.2 3.6 13 3 30.6 5.4 18 4 24.8 5.2 17 4 25.4 6.6 21 5 17.8 3.6 10 5 15.9 4.1 9 2 1 19.6 4.7 12 4 1 14.1 5.4 10 2 28.4 5.8 17 2 29.5 6.8 18 3 26.3 3.3 22 3 29.2 5.3 22 4 18.3 4.1 8 4 21.5 6.2 9 5 20.8 5.7 11 5 25.5 6.4 22