An appliance drawing 7.5 kW of power runs for 3 hours. How many kilowatt-hours does it consume?

• A. 22.5 kWh
• B. 15 kWh
• C. 30 kWh
• D. 37.5 kWh

Answer: (A)

Energy use is found by multiplying power by time, and the kilowatt-hour is the unit of energy. If an appliance pulls 7.5 kilowatts for 3 hours, the energy it consumes is 7.5 × 3 = 22.5 kilowatt-hours. The other numbers come from multiplying by different run times (2 hours gives 15 kWh, 4 hours gives 30 kWh, 5 hours gives 37.5 kWh), but for 3 hours the correct amount is 22.5 kWh.