For the following exercise, refer to the information given below. Round all answers to the nearest integer. In a biology experiment, let /(t) be the number of bacteria in a colony after t hours, where t = 0 corresponds to the time the experiment begins. Suppose that during the period from t = 4 hours to t = 8 hours the number of bacteria is modeled by the exponential function /(t) = et. (See figure below.) 3000 2000 1000 5 7 8 N(t) = et, 4 s t s 8 (a) Find the average rate of change of the population over the time period 6 s t s 7. bacteria per hour (b) What is the instantaneous rate of change of the population at t = 4 hr? At t = 4.5 hr? at t = 4 hr bacteria per hour at t = 4.5 hr bacteria per hour