Question

Jessica's parents are always telling her to turn off the lights when she leaves her room. The fixture in Jessica's room requires four bulbs that each use 75 watts of

electricity when they're on.
a. Jessica's parents estimate that she leaves the lights on unnecessarily for 2.5 hours per day. How many watt-hours of electricity are used by these bulbs during 2.5
hours?
b. Approximately how many kilowatt-hours of electricity are used in a year to keep these bulbs lit for 2.5 hours per day?
C. At a cost of $0.12 per kilowatt-hour, how much money is wasted per year by keeping these lights on unnecessarily? Round to the nearest dollar.
d. If five million people keep lights on as Jessica does, how much is wasted in unnecessary electric expenses?

Answer 1

a.) 750

b.) 273.75

c.) $33.00

d.) $165,000,000.00

Answer 2

Explanation:

4*75 = 300 watts ( her light)

a) 2.5*300=750 w/h

b) 365*750 = 273.75 Kw/h

c) (0.12)*273.75 = $32.85

d) 32.85 * 5,000,000 = $164,250,000.00