6-29. Two pumps are being considered for service in Africa. Each can draw water from a depth of 50 meters and both pumps deliver 60 horsepower (output) to the pumping operation. One of the pumps must be selected. It is expected that the pump will be in use 800 hours per year. The following data are available. If electricity costs $0.14 per kilowatt-hour, which pump should be selected if the MARR is 8% per year? Recall that 1 hp = 0.746 kW. What is the basic trade-off being made in this problem? (6.5) Pump A Pump B Capital investment $2,400 $2,000 Electrical efficiency 0.92 0.80 Annual maintenance cost $320 $200 Useful life 3 years 6 years