2 Heat is transferred through a plane wall from the inside of a room at 28C to the outside air at 4C. The convective heat transfer coefficients at the inside and outside surfaces are 15 and 39 W/(m2 K), respectively. The thermal resistance of a unit area of the wall is 0.7 m2K/W. Calculate the temperature at the outer surface of the wall and the rate of heat flow through the wall per unit area. [