possible The rate at which a machine operator's efficiency, E (expressed as a percentage), changes with respect to time t is given by dE dt =30 - 8t, where t is the number of hours the operator has been at work. G a) Find E(t), given that the operator's efficiency after working 2 hr is 77%; that is, E(2) = 77. b) Use the answer in part (a) to find the operator's efficiency after 3 hr; after 5 hr. n . . . ar a) E(t) = R b) The operator's efficiency after 3 hours is % ble The operator's efficiency after 5 hours is % se uni