An insulation system around a cylindrical pipe consists of two different layers. The first layer immediately on the outer surface of the pipe is made of glass wool and the second one is constructed using plaster of Paris. The cylinder diameter is 10 cm and each insulating layer is 1 cm thick. The thermal conductivity of the glass wool is 0.04 W/m °C and that of the plaster is 0.06 W/m °C. The cylinder carries hot oil at a temperature of 92 °C, and the atmospheric temperature outside is 15 °C. If the heat transfer coefficient from the outer surface of the insulation to the atmosphere is 15 W/m2 °C, calculate the temperature at the interface between the two insulating materials and on the outer surface.