What does running a 1500 W heater for 4 hours cost?

Question

A space heater draws 1500 watts. You run it for 4 hours, and electricity costs \0.20 per kilowatt-hour. Solve in your head. What does that session cost? Aim: under 20 seconds.

Accepted Answer

Convert watts to kilowatts, then multiply by hours to get energy: 1500 	ext{ W} = 1.5 	ext{ kW}, \qquad 1.5 	ext{ kW} 	imes 4 	ext{ h} = 6 	ext{ kWh.} Multiply by the price: 6 	ext{ kWh} 	imes \0.20 = \1.20. Takeaway. A kilowatt-hour is simply "one kilowatt for one hour." Watts to kilowatts (divide by 1000), times hours, times price, three clean steps. A 1.5 kW device costs about 30 cents an hour at 20 cents per kWh.

What does running a 1500 W heater for 4 hours cost?

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