a family goes on vacation for a week and leaves on a fan that consumes electricity at the rate of 200 watts. If the electricity is $0.14/kWh, how much does it cost to run the fan during this time?
T = 7days/week * 24h/day = 168 h.
0.2kW * 168h = 33.6 kWh Used.
Cost = $0.14/kWh * 33.6kWh = $4.70