The north wall of an electrically heated home is 20 ft long, 10 ft high, and 1 ft thick. It is made of brick whose thermal conductivity is k = 0.42 Btu/h·ft·°F. On a certain winter night, the temperatures of the inner and the outer surfaces of the wall are measured to be at about 62°F and 36°F, respectively, for a period of 8 h. Determine (a) the rate of heat loss through the wall that night and (b) the cost of that heat loss to the home owner if the cost of electricity is $0.07/kWh.