by R(t) = 20(0.86). 4. [9 marks] The resale value R (in thousands of dollars) of a company car after t years is estimated to be given (a) Determine the function for the rate of depreciation of the car. b) Use the differential to approximate the change in value (to the closest dollar) for each of the following time periods. Be sure to include units and a concluding statement for both questions. i. From the end of the 10th year after purchase until the end of the 12th year. ii. From the end of the 10th year (120 month) after purchase until the end of the next month (121st month) (c) Calculate the actual change of the value of the car over the two time periods in part (b). Round each result to the nearest dollar and include units and a concluding statement for both questions. (d) One of the values obtained in part (b) is a much better approximation to the true change value found in (c). Comment on why using the differential for either (i) or (ii) was not a great approximation