Math If the child's room is lit with two 10 watt bulbs for one extra hour a day for everyday of the year, and the cost of energy is $0.068 per kilowatt*hour (kWh), how much money is wasted on lighting Asked by kairi789 on 30 Sep 08:50 Last updated by anonymous on 27 Nov 11:18
2 bulbs = 20 watts for 1 hr a day is 20watt-hours=0.020 kW-hours. For a whole year of 365 days this is 0.02*365=7.3kW-hrs. Cost is 7.3*0.068=$0.4964 or about 50 cents. Posted by Rod