Question

note: please make sure to properly format your answers. all dollar figures in the answers need to include the dollar sign and any amount over 1,000 should include the comma ($2,354.67). all percentage values in the answers need to include a percentage sign (%). for all items without specific rounding instructions, round your answers to two decimal places, show both decimal places (5.06). jessicas parents are always telling her to turn off the lights when she leaves her room. the fixture in jessicas room requires four bulbs that each use 75 watts of electricity when theyre on. a. jessicas 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 for 2.5 hours per day? d. if five million people keep lights on as jessica does, how much is wasted in unnecessary electric expenses? round to the nearest dollar.

Explanation:

Step1: Calculate daily watt - hours for 4 bulbs

Each bulb is 75 watts and there are 4 bulbs, and they are on for 2.5 hours. Watt - hours per day = 75×4×2.5 = 750 watt - hours.

Step2: Convert daily watt - hours to annual kilowatt - hours

There are 365 days in a year. First, convert 750 watt - hours to kilowatt - hours (1 kilowatt - hour = 1000 watt - hours), so daily kilowatt - hours is $\frac{750}{1000}=0.75$ kilowatt - hours. Annual kilowatt - hours = 0.75×365 = 273.75 kilowatt - hours.

Step3: Calculate annual cost for Jessica

Cost per kilowatt - hour is $0.12. Annual cost for Jessica = 273.75×0.12 = $32.85.

Step4: Calculate cost for 5 million people

If 5 million (5000000) people are doing the same, total wasted cost = 32.85×5000000 = $164250000.

Answer:

$164250000