A mixture of acetone and water is to be separated in a continuous countercurrent extraction by using 1,1,2-trichloroethane. It contains 70wt% acetone and is fed at a rate of 2000lb/hr. The final extract should contain 90wt% acetone when trichloroethane has been completely removed. If the operation proceeds at three stages, what is the \% recovery of acetone? At what rate is pure solvent being used