In an electrically heated home, the temperature of the ground in contact with a concrete basement wall is 13.8 0C. The temperature at the inside surface of the wall is 21.7 0C. The wall is 0.12 m thick and has an area of 7.7 m2. Assume that one kilowatt hour of electrical energy costs $010. How many hours are required for one dollar's worth of energy to be conducted through the wall? Number Units 9