A pharmaceutical manufacturer wants to investigate the bioactivity of a new drug. A completely randomized single-factor experiment was conducted with three dosage levels, and the following results were obtained.

Dosage Observations 20 g 24 28 37 30 30 g 37 44 31 35 40 g 42 47 52 38

(a) Is there evidence to indicate that dosage level affects bioactivity? Use ???? = 0.05.

(b) If it is appropriate to do so, make comparisons between the pairs of means. What conclusions can you draw?

(c) Analyze the residuals from this experiment and comment on model adequacy.