A methanol$-$ethanol mixture is

fed to the distillation column

shown in the figure. Assuming a

constant relative volatility of

$1\mathrm{.}745,$ and Murphree liquid

efficiency, EML, of $50\%,$ and

using McCabe$-$ Thiele method,

determine

a$.$ the number of trays

required,

b$.$ the optimal stage location

for the feed,

c$.$ the stage where the liquid

side stream should be

withdrawn.