The inside dimensions of a refrigerated box is 2m x 1 m x 1.2 m. It is covered with insulation 50 mm thick and then a liner 5 mm thick. It is required to extract 150 W from the box. Simplifying the problem to a plain flat surface calculate the inside temperature when the outer surface is maintained at 20oC. The thermal conductivity of the insulation is 0.043 W/m K and 0.2 W/m K for the liner.