*6-13. Reconstruct the equipment replacement model of Example 6.3-1, assuming that a car must be kept in service for at least 2 years, with a maximum service life of 4 years. The planning horizon is from the start of year 1 to the end of year 5. The following table provides the necessary data: Replacement cost ($) for given years in operation 2 Year acquired 3 6800 UAWNW 3800 4000 4200 4800 5300 4100 4800 5300 5700 7000 7200 6.3 Shortest-Route Problem 223 9800 5400 7100 4000 4300 4800 4900 o 40 - 4300 - 6200 8700 FIGURE 6.7 Equipment replacement problem as a shortest-route model Replacement cost ($) for given years in operation Equipment cada