A 40-cm-thick brick wall (k = 0.72 W/mK, and = 1.6 10 -6 m 2

A 40-cm-thick brick wall (k = 0.72 W/m·K, and α = 1.6 × 10^-6 m²/s) is heated to an average temperature of 18°C by the heating system and the solar radiation incident on it during the day. During the night, the outer surface of the wall is exposed to cold air at 23°C with an average heat transfer coefficient of 20 W/m²·K, determine the wall temperatures at distances 15, 30, and 40 cm from the outer surface for a period of 2 h.