Ken has five 200W security lights on outside of home. How much energy do the security lights use in 8 hrs?

Question

If the cost of electricity is 8 cents per kWh,what is the cost of operating the security lights ?

Please help I'm not sure which formula to use?

Answer 1

5*200 = 1,000 watts = 1 kw

1 * 8 = 8 kw hr

8 cents/kw h * 8 kw h = 64 cents every 8 hours