Equilibrium K values

ln(K) = (-1166846/T^2) + 7.72668 - 0.92213 ------ i-Butane

ln(K) = (-1481583/T^2) + 7.58071 - 0.93159 ------ i-Pentane

P is in psia and T is in R

(A) Find the number of Equilibrium trays in the stripping section

(B) Calculate the Vapor composition leaving the reboiler and the last 2 trays

A distillation column receives a feed that is 40 mole \% ibutane and 60 mole \% i-pentane. Feed is saturated liquid at 1,000 lbmol/hr. The column is at 14.7 psia. A distillate that is 95 mole \% i-butane is desired. A total condenser is used. Reflux is a saturated liquid. The external reflux ratio is L0/D=2.3 Bottoms from the partial reboiler is 9 mole \% i-butane