Fifty-thousand kg/h of flaked soybeans, containing 20 wt% oil, is to be leached of the oil with the same flow rate of n-hexane in a countercurrent-flow system consisting of an ideal leaching stage and three ideal washing stages. Experiments show that the underflow from each stage will contain 0.8 kg liquid/kg soybeans (oil-free basis).

(a) Determine the % recovery of oil in the final extract.

(b) If leaching requires three of the four stages, such that one-third of the leaching occurs in each of these three stages, followed by just one true washing stage, determine the % recovery of oil in the final extract.