Question

In a certain city, electricity costs $ 0.13 per kW ⋅ h . What is the annual cost for electricity to power a lamppost for 8.00 h per day with a 100. W incandescent light bulb versus an energy efficient 25 W fluorescent bulb that produces the same amount of light? Assume 1 year = 365 days .

Answer 1

37.96usd , 9.49usd

Step-by-step explanation:

From the data given we have

cost of electricity= $0.13,

and annual cost of electricity is express as

Annual cost= power *hours*days*cost of electricity

note the unit of power must be in kilowatt(Kw),

a. to determine the cost of running 100w we first convert to kw

`1w=0.001kw\\100w=0.1kw\\`

Hence the annual cost of running it 8.00 hours per day is calculated as

`annual cost=0.1*8*365*0.13\\annual cost=37.96 USD`

b. to determine the cost of running 25w we first convert to kw

`1w=0.001kw\\25w=0.025kw\\`

Hence the annual cost of running it 8.00 hours per day is calculated as
`annual cost=0.025*8*365*0.13\\annual cost=9.49 USD`

Hence from the answers we can conclude that less amount of money required to run the 25w incandescent bulb compare to the 100w