Q$4.$

Acetone is to be extracted from a $30wt\%$ acetone $($A$)$ and $70wt\%$ ethyl acetate $($C$)$ feed at $30C,$ using pure water $(S)$ as the solvent, by the cascade. The final raffinate is to contain $5$ w $\%$ acetone on a water$-$free basis. Determine the minimum solvent$-$tofeed ratios and the equilibrium stages required for two intermediate $\frac{S}{F}$ ratios.