A bus company has a four-year-old natural gas powered bus that was initially purchased for $90,000. This bus can be kept in service for an additional four years, or it can be sold for $31,000 and replaced by a new one. The purchase price of the replacement machine is $75,000. 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 8%, Defender: Market value at EOY EOY1: $24,800 EOY2: $18,600 EOY3: $6,200 EOY4: $0 Defender: Operating and maintenance costs at EOY EOY1: $24,000 EOY2: $26,400 EOY3: $33,600 EOY4: $38,400 Challenger: Market value at EOY EOY1: $60,000 EOY2: $56,250 EOY3: $45,000 EOY4: $37,500 Challenger: Operating and maintenance costs at EOY EOY1: $19,000 EOY2: $20,900 EOY3: $23,750 EOY4: $28,500 (a) determine the economic life of the challenger and enter its EUAC for that year (b) determine the total marginal cost for the defender in year 3. A bus company has a four-year-old natural gas powered bus that was initially purchased for $90,000. This bus can be kept in service for an additional four years, or it can be sold for $31,000 and replaced by a new one. The purchase price of the replacement machine is $75,000. 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 8%, Defender: Market value at EOY EOY1: $24,800 EOY2: $18,600 EOY3: $6,200 EOY4: $0 Defender: Operating and maintenance costs at EOY EOY1: $24,000 EOY2: $26,400 EOY3: $33,600 EOY4: $38,400 Challenger: Market value at EOY EOY1: $60,000 EOY2: $56,250 EOY3: $45,000 EOY4: $37,500 Challenger: Operating and maintenance costs at EOY EOY1: $19,000 EOY2: $20,900 EOY3: $23,750 EOY4: $28,500 (a) determine the economic life of the challenger and enter its EUAC for that year (b) determine the total marginal cost for the defender in year 3