] 6.1. An engineer is interested in the effects of cutting speed (A), tool geometry (B), and cutting angle (C) on the life (in hours) of a machine tool. Two levels of each factor are chosen, and three replicates of a 23 factorial design are run. The results are as follows: Treatment Renlicate A B C Combination I II III - (1) 22 31 25 + - - a 32 43 29 + b 35 34 50 + + ab 55 47 46 + c 44 45 38 + + ac 40 37 36 + + be 60 50 54 + + + abc 39 41 47