If \(1000 \mathrm{~kg} / \mathrm{h}\) of a cottonseed oil-oleic acid solution containing \(25 \mathrm{wt} \%\) acid is to be continuously separated into two products containing 2 and \(90 \mathrm{wt} \%\) acid (solvent-free compositions) by countercurrent extraction with propane, calculate:

(a) The minimum number of theoretical stages required.

(b) The minimum external extract/reflux ratio required.

(c) For an external extract/reflux ratio of 4.5, the number of theoretical stages, the position of the feed stage, and the quantities, in \(\mathrm{kg} / \mathrm{h}\), of the important streams.