The separation of toluene-ethanol mixtures was studied using a polyethylene membrane in a small pervaporation cell. With one atmosphere pressure and 30°C on the 361 upstream side and full vacuum on the permeate side, the pure-component permeation rates were 3.89 x 10^-4 kg/m²·s for toluene and 0.273 x 10^-4 kg/m²·s for ethanol. With 50 volume percent toluene in the liquid, the fluxes were 2.5 x 10^-4 kg/m²·s for toluene and 0.5 x 10^-5 kg/m²·s for ethanol. Calculate the selectivity based on the mole fraction of toluene in the permeate and the solution. Compare this with the selectivity predicted from the pure-component data, neglecting interactions between the components.