A solid is being dried in the linear drying rate regime from moisture content Xo to XF$.$ The drying rate is zero at X $=0$ and the critical moisture content is the same as the initial moisture Xo$.$ The drying time for M $=($Ls$/$ARc$)$ is $($where$,$ L $=$ total mass of dry solid, A $=$ totalsurface area for drying Rc $=$ Constant maximum drying rate per unit area X $=$ moisture content $($in mass of water$/$mass of dry solids$))$

M$($Xo $-$ XF$)$

M$($Xo$/$XF$)$

M ln$($Xo$/$XF$)$

MXo ln$($Xo$/$XF$)$