How long would it take for a 60 w lamp to consume 30.24 kilowatt-hours of power?

A kilowatt-hour measures energy, which is slightly different than defining power. The computation for this question comes in the following form: 30.24 kW-hour = 30240 watt-hour (because 1 kW = 1000 watts); 30240 watt-hour/60 watts = 504 hours. This is known as dimensional analysis.