A sheet materid measuring $1m^2$ and $5cm$ thick is to be dried from $45\%$ Ho $5\%$ moishure under constant drying conditions. The dry densily of the material is $450k\frac{g}{m^3}$ and its equitibrium moishere content is $2\%.$ The avitable doying surface is $i{m}^2.$ Experiment's show that the rate of drying was constant at $4\mathrm{.}8k\frac{g}{m}{m}^2,$ between morbhure content of $45\%$ and $20\%.$ Below $20\%$ the rate decreare linearly. calculate the tofal time requised to dry the materid from