Two types of 150-horsepower (HP) motors are being considered for installationat a municipal sewage-treatment plant. The first motor costs $4,500 and has anoperating efficiency of 83% at full load. The second motor costs $3,600 and hasan efficiency rating of 80% at full load. Both motors are projected to have zerosalvage value after a life of 10 years. The annual operating and maintenance cost(excepting power cost) amounts to 15% of the original cost of each motor. Thepower costs are a flat 5 cents per kilowatt-hour. What would be the minimumnumber of hours of full-load operation per year necessary to justify the purchaseof the more expensive motor at i = 6%? (1HP = 0.7457 kilowatt)(a) 851 hours to 900 hours (b) 901 hours to 950 hours(c) 951 hours to 1,000 hours (d) 1,001 hours to 1,050 hours
Two types of 150-horsepower (HP) motors are being considered for installation
at a municipal sewage-treatment plant. The first motor costs $4,500 and has an
operating efficiency of 83% at full load. The second motor costs $3,600 and has
an efficiency rating of 80% at full load. Both motors are projected to have zero
salvage value after a life of 10 years. The annual operating and maintenance cost
(excepting power cost) amounts to 15% of the original cost of each motor. The
power costs are a flat 5 cents per kilowatt-hour. What would be the minimum
number of hours of full-load operation per year necessary to justify the purchase
of the more expensive motor at i = 6%? (1HP = 0.7457 kilowatt)
(a) 851 hours to 900 hours (b) 901 hours to 950 hours
(c) 951 hours to 1,000 hours (d) 1,001 hours to 1,050 hours
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