Quantitative reasoning

Question

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 150-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 15 watts of power?

Answer 1

1 kilowatt is 1,000 watts

150 wats = 150/1000 = 15/100 = .15 kilowatts = 3/20 kilowatts

10 cents per hour for 11 hours = $1.10

multiply 110 by 3/20 = 33/2

= $16.50 for 150 watts for 11 hours

15 watts is 10 times less expensive than 150 watts

costing only $1.65 for 11 hours

cost saving = 16.5 -1.65= $14.85 per day

cost saving for a year = 365.25 x 14.85 = $5,427.62