An energy-efficient lightbulb, taking in 23.0 W of power, can produce the same l

Question

An energy-efficient lightbulb, taking in 23.0 W of power, can produce the same level of brightness as a conventional lightbulb operating at power 100 W. The lifetime of the energy-efficient bulb is 10 000 h and its purchase price is $4.10, whereas the conventional bulb has lifetime 750 h and costs $0.46 per bulb. Determine the total savings obtained by using one energy-efficient bulb over its lifetime as opposed to using conventional bulbs over the same time period. Assume an energy cost of $0.20 per kilowatt-hour.

Explanation / Answer

Energy consumed by energy efficent bulb for 10,000 hours is

E=10000*(23/1000) =230 KWh

Cost of energy efficent bulb for 10,000 hour including purchase price s

C=230*0.2+4.1=$50.1

For Conventional bulb

Number of of conventional bulbs used for 10,000 hour si

N=10000/750=14 bulbs

Purchase cost of bulbs

Cp=14*0.46=$6.44

Energy consumed by conventional bulb is

E=10000*(100/1000)=1000

Cost of Conventional bulb for 10,000 hour including purchase price is

C=1000*0.2+6.44=$206.44

so savings are

savings =206.44-50.1=$156.34

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