Your refrigerator uses an average of 350watts and your utility company charges $.10 per kilowatt-hour of energy (including taxes and fees). How much does it cost you to run your refrigerator for a year? Explain.
The cost of running the fridge for a year = (Cost of energy per hour) x (Energy used in 1 year)
We are given the cost of energy per hour: $0.10 per kW-hr
Let's get the power used in 1 year in terms of kW and hr
kilowatt -> 1000 watts (kilo = a thousand)
350 W x (1 W/1000 kW) = 0.35 kW
So, the fridge uses 0.35 kW of power.
1 year = 365 days = 8760 hours
Now multiply it out with your calculator:
( 0.35 kW )( 8760 hr )( $0.10 /kW hr)
Hope this helps!