A distillation column is separating 900 moles /hr of a mixture of 25 mole \% ethanol and 75 mole % water at a pressure of 1 atmosphere. The feed enters as a subcooled liquid that condenses one mole of vapor on the feed plate for every 4 moles of feed. The column has a partial condenser and uses open steam injection or heating with a flow rate S. We desire a distillate product yD=0.80 and a bottom product xB=0.08. Constant molal overflow is valid. The steam used is pure saturated water vapor. a. Find the minimum external reflux ratio. b. Use L0/D=2.5(L0/D)minimum,, and find the number of real stages and the real optimum feed location if the Murphree vapor efficiency is 2/3 for all stages. c. Find the steam flow rate S used