An Efficiency Study at a Certain Factory Indicates That an Average

Short Answer

An efficiency study at a certain factory indicates that an average worker who arrives on the job at 8:00 A.M. will have produced $Q ( t ) = - t ^ { 3 } + 6 t ^ { 2 } + 18 t$ units t hours later. At what rate, in units/hour, is the worker's rate of production changing with respect to time at 9:00 A.M.?