A city water and waste-water department has a four-year-old sludge pump that was initially purchased for $65,000. This pump can be kept in service for an additional four years, or it can be sold now for $29,500 and replaced by a new pump. The purchase price of the replacement pump is $49,000. The projected MVs and operating and maintenance costs over the four-year planning horizon are shown in the table that follows. Assuming the MARR is 10%, (a) determine the economic life of the challenger and (b) determine when the defender should be replaced. EUAC Defender Year MV at EOY O&M Costs Marginal cost 1 $25,500 $24,500 $31,450 2 21,500 27,000 33,550 3 17,500 29,500 35,650 4 13,500 32,000 37,750 Click the icon to view the interest and annuity table for discrete compounding when the MARR is 10% per year. Challenger MV at EOY O&M Costs $35,000 $13500 27,000 16,000 19,000 18,500 11,000 21,000 $33,500 30,643 30,207 30,356 a. The economic life of the challenger is year(s). (Round to the nearest whole number.) b. The defender should be A. replaced now B. kept for at least one more year A city water and waste-water department has a four-year-old sludge pump that was initially purchased for $65,000. This pump can be kept in service for an additional four years, or it can be sold now for $29,500 and replaced by a new pump. The purchase price of the replacement pump is $49,000. The projected MVs and operating and maintenance costs over the four-year planning horizon are shown in the table that follows. Assuming the MARR is 10%, (a) determine the economic life of the challenger and (b) determine when the defender should be replaced. EUAC Defender Year MV at EOY O&M Costs Marginal cost 1 $25,500 $24,500 $31,450 2 21,500 27,000 33,550 3 17,500 29,500 35,650 4 13,500 32,000 37,750 Click the icon to view the interest and annuity table for discrete compounding when the MARR is 10% per year. Challenger MV at EOY O&M Costs $35,000 $13500 27,000 16,000 19,000 18,500 11,000 21,000 $33,500 30,643 30,207 30,356 a. The economic life of the challenger is year(s). (Round to the nearest whole number.) b. The defender should be A. replaced now B. kept for at least one more year