Previous Problem List Next (1 point) An efficiency study of the morning shift at a certain factory indicates that an average worker who arrives on the job at 8 : 00 A.M. will have assembled f (x) =-x3 + 12x2 + 15x units x hours later. a) Derive a formula for the rate at which the worker will be assembling units after x hours. r(xx) = b) At what rate will the worker be assembling units at 9 : 00 A.M.? The worker will be assembling units per hour. c) How many units will the worker actually assemble between 9 : 00 A.M. and 10 : 00 A.M. ? The worker will assemble units. Note: You can earn partial credit on this