An engineer is interested in the effects of cutting speed (A) and tool geometry (B) on the life (in hours) of a machine tool. Two levels of each factor are chosen, and four replicates of a completely randomized experiment were run. The results are shown in the following table: Treatment Replicate A B combination 1 2 3 4 (1) 35 13 15 10 + a 13 39 11 16 - b 39 16 42 44 + + ab 20 21 58 45 (a). Estimate the factor effects and comments on their sizes