A large wall of thickness 0.05 m and thermal conductivity 0.65 W/mK has a front surface with an emissivity of 0.8. At this surface there is radiation exchange with the surroundings and convection heat transfer to the air. The air and surroundings are at 295 K, and the convection heat transfer coefficient is 20 W/m2 K. If the front surface temperature of the wall is 425 K, what is the rear surface temperature? (Ans = 712K)