It is derired to dry a cortain type of fibre board $m$ sheets $0\mathrm{.}13m0\mathrm{.}162m0\mathrm{.}071m$ from $59\%$ to $4\%$ moishuse $($wet banis$)$ content. The rate of drying at constant rate period was found to be $8\mathrm{.}0kg$ The critical moishure content was $24\mathrm{.}8\%$ and the $m^{2}rr$ equilibnum moishere content was $1\mathrm{.}0\%.$ The fibre board is to be dried from one side only and has time requised for drying. Assume the falling rate

is linear.