22. Three different washing machines were employed to test four different detergents.

The following data give a coded score of the effectiveness of each washing.

(a) Estimate the improvement in mean value when using detergent 1 over using detergents (i) 2; (ii) 3; (iii) 4.

(b) Estimate the improvement in mean value when using machine 3 as opposed to using machine (i) 1; (ii) 2.

(c) Test the hypothesis that the detergent used does not affect the score.

(d) Test the hypothesis that the machine used does not affect the score.
Use, in both

(c) and (d), the 5 percent level of significance.

Transcribed Image Text:

Machine 1 2 3 Detergent 1 53 50 59 Detergent 2 54 54 60 Detergent 3 56 58 62 Detergent 4 50 45 57