800 g of a solution has solute 40%  by weight, on cooling the  solution  100 g of the solute is precipitated. The weight percentage composition of the solute in the filtrate (after removing precipitate) is

Solute in 800 g solution =800×40100=320gWater in solution = 800 - 320 = 480 gSolute removed = 100gSolute left in solution = 320 - 100 = 220 g in 480 g waterTotal weight of solution = 220 + 480 = 700 g  Thus, % concentration =220700×100=31.4%