-Calculate the rate of heat loss across a wall of thickness 6  inch with an inside temp.200°F and outer side of 60 °F and  an area of 2 ft2. The thermal conductivity is 30.

Calculate  the % heat saving if this wall is covered by a 2 inch  thickness insulator on the colder surface with thermal  conductivity = 0.02 when the outer surface temp. is 10 ºF and an area of 2 ft2