2-39 LED light bulbs are more energy efficient, last longer, cost more, and have a smaller environmental impact from manufacture to recycling or disposal.The question is which costs less: incandescent,compact

fluorescent (CFL), or LED lights? (a) Ignore the time value of money. What is the average cost per hour for 25,000 hours of lighting in a community with $0.15//kWh electricity for each choice? (b) If the light is on 5%, 30%, or 60% of the time,how long until does it take for the 25,000 hours? (c) Which type of light should a homeowner buy?

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