4. Suppose that a bacterial population changes with time according to the function $P(t)=40-10e^{-0.2t}$. In this formula,
the population, P, is measured in millions of bacteria and time, t, in hours.
((Numerical answers must have 2 decimal places. Include units with your answers.)
(a) Find the average rate of change (ARC) between t=1 and t = 2 hours.
(b) Find the instantaneous rate of change (IRC) of the population at t = 2 hours.
(c) Is the population increasing, decreasing, or not changing at t=2 hours? Justify your answer.