Part II (80 Points) Short Answers. Please answer the following four questions. Your answers should be brief but as complete as possible. You may use the back of the page if more writing space is needed. 1 (a) The present value of benefits of a public project of scale S is PVB =16SS2 and the present value of its costs is PVC=3S2. Use calculus to determine the optimum scale of this project. Also illustrate your answer in a diagram. [10 points].