Engineering Economics or Economy - Typical Problems

1. Repairs to a factory roof can be made today for $4,000. If repairs are postponed, it will have to be replaced in 3 years for $6,000. Both the repaired roof and new roof will have similar technical life and last long. If the company's minimum required rate of return is 30%, should the repairs be made?

Sppwf (32%, 3 years) = 0.435

2. By spending $30,000 for a conveyor, a factory expects to save $6,000 a year for the next 7 years in the cost of handling material. The conveyor belt will have zero salvage value at that end of 7 years. If the cost of capital for the project is 18%, should the company invest in this project?

Uspwf(18%,7 years) = 3.812

3. A company can overhaul a machine now for $2000. It can wait unit the end of the year also. But during the year it will suffer a cost $400 due to idle labor. If the cost of capital is 20%, what is the right decision?

Spfwf(20%,1year) = 1.2

4. A machine needs to be maintained at a cost of $500 at the end of the year, and this cost is expected to increase by $50 a year over its 10 years further life. A overhaul of the machine costs $2000$ and this will reduce the maintenace expenditure to $100 per year. Should the company go for the overhaul if its minimum rate of return required is 20%?

Uspwf (20%,10 years) = 4.193

5. A company can purchase a new special-purpose lathe for $7,500 installed cost. The annual cost of running this machine that includes labor, power, and maintenance, is $2,500. The other alternative is a general purpose machine that can be installed for $4,500 and the anual cost is $3,250 a year. The life of both the machines is expected to be 10 years and the salvage values are expected to be $750 and $500. If the company's minimum required rate of return is 15%, which machine should be recommended?

Sppwf (15%,10years) = 0.247; Uspwf (15%,10 years) = 5.019

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