Question

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 50 watts of electricity when theyre on. if five million people keep lights on as jessica does, how much is wasted in unnecessary electric expenses?

Explanation:

Step1: Calculate power of lights in Jessica's room

There are 4 bulbs, each 50 watts, so total power $P = 4\times50=200$ watts.

Step2: Calculate wasted electricity for 5 million people

If 1 person wastes 200 watts, for 5 million ($5\times10^{6}$) people, wasted power $W=200\times5\times 10^{6}=1\times10^{9}$ watts or 1 gigawatt.

Answer:

1 gigawatt