You have 20 single-pane windows in your house: all with dimensions of 2 ft X 4 ft. After completing this lab exercise, you decide to conserve energy by replacing them with double-pane windows. The cost of replacing all of the windows in your house would be $3.00 per square foot, and the cost of electricity is 12 cents per kWh. What is the payback period of replacing all of your single-pane windows with double-pane windows?