It is desired to design a continuous rectification column to separate $15000$ kg$/$h of a mixture containing $40\%$ benzene and $60\%$ toluene, in order to obtain a head product of $97\%$ benzene and a tail product of $98\%$ toluene. All percentages are by weight and a reflux ratio of $3\mathrm{.}5$ moles per mole of product will be used. Calculate: