Question 1196031
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Your utility company charges 10 cents per​ kilowatt-hour of electricity. 
Complete parts​ (a) and​ (b) below.
a. What is the daily cost of keeping lit a 100​-watt light bulb for 11 hours each​ day?
b. How much will you save in a year if you replace the bulb with an LED bulb that provides 
the same amount of light using only 20 watts of​ power?
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<pre>
(a)  100 watts = 0.1 kilowatt.

     The daily consumption of energy by 100-watt light bulb is  0.1*11 = 1.1 kilowatt-hours.

     The daily cost of the energy by 100-watt light bulb is 10*1.1 = 11 cents.     <U>ANSWER</U>



(b)  1 year = 365 days.

     The cost of the energy by 100-watt light bulb per year is 365*11 = 803 cents = 4015 cents = $40.15.


     The daily consumption of energy by 20-watt LED bulb is 0.02*11 = 0.22 kilowatt-hours.

     The daily cost of the energy by 20-watt LED bulb is 10*0.22 = 2.2 cents.

     The cost of the energy by 20-watt LED bulb per year is 365*2.2 = 803 cents = $8.03.


     You will save on the energy payment $40.15 - $8.03 = $32.12 per year.    <U>ANSWER</U>
</pre>

Solved.


Quite simple calculations.