14. A construction company wants to determine the optimal replacement policy for the earth mover it owns. The company has a policy of not keeping an earth mover for more than five years, and has estimated the annual operating costs and trade-in values for earth movers during each of the five years they might be kept as shown in the following table: Assume that new earth movers currently cost $25,000 and are increasing in cost by 4.5% per year. The company wants to determine when it should plan on replacing its current, two-year-old earth mover. Use a five-year planning horizon. a. Draw the network representation of this problem. b. Implement your model in a spreadsheet and solve it. What is the optimal solution? c. What other aspects of this problem might an analyst want to consider