Design the number of theoretical plates and the reflux, $3$ Rmin, of a column to separate $15\%$ propane, $15\%$ butane, $30\%$ pentane, and $40\%$ hexane. At $366\mathrm{.}5$ K and $689\mathrm{.}5$ kPa.

$90\%$ propane is desired at the top.