Recall that the monthly revenue R (in thousands of dollars) of a bakery store t months can be modelled by R(t) = 1/12 t^3 - t^2 + 15/4 t, 0 lessthanorequalto t lessthanorequalto 8. We shall find the intervals on which R is increasing or R is decreasing by following the following steps. Find the derivative R'(t). Find values (if any) of t when R'(t) = 0. Find values (if any) of t when R'(t) is undefined. Use the values found in (b) and (c) to test the sign of R'(t) on some particular intervals.