How much water should be added to a 96% solution weighing 218 g to get an 84% solution?

1) Find the mass of the solute with the original solution. To do this, we multiply the mass of the solution by the mass fraction of the substance and divide by one hundred percent: 96 * 218/100 = 209g.
2) Because the amount of the solute remains the same, then we can find the mass of the solution with the mass fraction of the substance 84%. To do this, we multiply the mass of the solute by one hundred percent and divide by the mass fraction: 209 * 100/84 = 249g.
3) Find the mass of water. To do this, subtract the mass of the original from the mass of the resulting solution: 249 – 218 = 31g.
4) Find the volume of water. To do this, we divide the mass of water by its density: 31/1 = 31g – the answer.