A masonry brick wall 0.45 m thick has a temperature distribution at time, t = 0 which may be approximated by the expression T(K) = 520 + 330 sinπ (x/L) where L is the wall width and x is the distance from either surface. How long after both surfaces of this wall are exposed to air at 280 K will the center temperature of the wall be 360 K? The convective coefficient at both surface of the wall may be taken as 14 W/m² · K. What will the surface temperature be at this time?