A finely ground mixture of galena and limestone in the proportion of 1 to 4 by mass is subjected to elutriation by an upward-flowing stream of water flowing at a velocity of 5mm/s. Assuming that the size distribution for each material is the same and is as shown in the following table, estimate the percentage of galena in the material carried away and in the material left behind. The viscosity of water is 1mN s/m2 and stokes equation may be used. Diameter (m) 20 30 40 50 60 70 80 100 Undersize (% mass) 15 28 48 54 64 72 78 88 The densities of galena and limestone are 7500 and 2700kg/m3, respectively.