A new LED light bulb uses 10 watts of power.
Since energy = power × time, then the energy used for this light bulb can be found by multiplying the power times the time the bulb is lit. If the bulb is lit for one hour, the energy used will be 10 watt-hours or 10 Wh. If three 10 watt bulbs in one room are kept on for 5 hours, how many watt-hours of energy are used?
Parents sometimes yell at their children for leaving the light on in their bedroom when they aren't in the room. If the child's room is lit with two 10 watt bulbs for one extra hour a day for every day of the year (365), and the cost of energy is $0.068 per kilowatt-hour (kWh), how much money is wasted on lighting that isn't being used, to the nearest cent.