A feed consisting of 62 mol% para-dichlorobenzene in ortho-dichlorobenzene is to be separated by distillation at near atmospheric pressure into a distillate containing 98 mol% para isomer and bottoms containing 96 mol% ortho isomer. If a total condenser and partial reboiler are used, q = 0.9, average relative volatility = 1.154, and reflux/minimum reflux = 1.15, use the Fenske-Underwood-Gilliland procedure to estimate the number of theoretical stages required.