Dilute counter current immiscible extraction: A feed of $100\mathrm{.}0k\frac{g}{m}in$ of a $1\mathrm{.}25wt\%$ mixture of acetic acid in water is to be extracted with $1-$butanol at $1$atm pressure and $26\mathrm{.}7C.$ We desire an outlet concentration of $0\mathrm{.}25wt\%$ acetic acid in the exiting water. We have available a solvent stream that is $74\mathrm{.}0k\frac{g}{m}in$ of pure $1-$butanol and is added at the bottom of the column. Devise a scheme to perform this separation, find the outlet flow rate and concentration of the exiting $1-$butanol phase, and find the number of equilibrium contacts needed. $(7$ marks, A&A