An oven may be regarded as a cube, each side 1.2m long. The oven stands on thin legs and the heat transfer through each of the six faces is identical. The walls and doors are all made of a stainless steel lining (thermal conductivity 20W/mK) 2mm thick, a layer 75mm thick of insulating material (thermal conductivity 0.25W/mK) and a mild steel outer sheet (thermal conductivity 48.5W/mK) 3mm thick. If the inner wall temperature is 400oC and the outer surface temperature is 100oC calculate the rate of heat loss from the oven. Estimate the heat transfer coefficient between the oven and the surrounding air at 30oC