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Your utility company charges 14 cents per kilowatt-hour of electricity. Complete parts (a) and (b) below.
a. What is the daily cost of keeping lit a 150-watt light bulb for 8 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?
a. The daily cost of keeping lit a 150-watt light bulb for 8 hours each day is $
(Round to three decimal places as needed.)
b. The yearly savings of replacing the 150-watt light bulb with a 20-watt light bulb is
(Round to two decimal places as needed.)

Respuesta :

Answer:

P = 150 W * 60 sec/min * 60 min/hr =  540000 W-sec/hr

1 kW = 1000 W * 3600 sec = 3.6E6 W-sec

E (8 hrs) = 8 * .54E6 W-s = 4.32E6 W-sec

or E= 4.32/3.6 = 1.2 kW = .168 $/day

20/150 = .133 as much for a 20-watt bulb

For a LED bulb cost/day = .168 * .133 = $.022/da

Note 1 W = 1 Joule/sec

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