Problem:
Compact fluorescent lamps (CFLs) have become more popular in recent years, but do they make financial sense? Suppose a typical 60-watt incandescent light bulb costs $0.51 and lasts 1,000 hours. A 15-watt CFL, which provides the same light, costs $3.70 and lasts for 12,000 hours. A kilowatt-hour of electricity costs $0.127, which is about the national average. A kilowatt-hour is 1,000 watts for 1 hour.
Required:
Question: If you require a 10 percent return and use a light fixture 500 hours per year, what is the equivalent annual cost of each light bulb?
Note: Explain all calculation and formulas.