A batch of wet solid was dried on a tray dryer using constant drying conditions and a thickness of material on the tray of 25.4 mm. Only the top surface was exposed. The drying rate during the constant-rate period was R = 2.05 kg H_2O/h middot m^2 (0.42 lb_m H_2 O/h middot ft^2). The ratio Ls/A used was 24.4 kg dry solid/m^2 exposed surface (5.0 lbm dry solid/ft^2). The initial free moisture was = 0.55 and the critical moisture content Xc = 0.22 kg free moisture/kg dry solid. Calculate the time to dry a batch of this material from X-1 = 0.45 to X_2 = 0.30 using the same drying conditions but a thickness of 50.8 mm, with drying from the top and bottom surfaces.