Two 150-horsepower (HP) motors are being considered for installation at a municipal sewage-treatment plant. The first costs $4,500 and has an operating efficiency of 83%. The second costs $3,600 and has an operating efficiency of 80%. Both motors are projected to have zero salvage value after a life of 10 years. All the annual charges, such as insurance and maintenance, amount to a total of 15% of the original cost of each motor. If power cost is a flat 5 cents per kilowatt-hour, which alternative should be chosen at 5,000 operating hours per year? Assume an interest rate of 6%. (A conversion factor you might find useful is 1HP = 746 watts = 0.746 kilowatts.)