Find the mass/volume percentage for a solution prepared from 15 grams of ethanol and a 100 millilitres of acetone and we're given the density of both of those solutions. So the first thing we need to do is remember what a mass/volume percentage looks like when we do that calculation. So we know we're going to have the mass, in units of grams over the volume, and that will be in units of milliliters. And, this mass will be of the solute, and the volume will be of the solution. So, it's going to include, both the solute and the solvent. So, what we look at first is figuring out which one is our solute. We see that ethanol is present in the smaller amount, so that's going to be our solute. And that the acetone is present in the larger amount, so that would be the solvent. And together, both of them make up the solution. So, if I need the mass of solute, I already have that information, that's given in the problem here, so I don't need to do the calculations for that. And it's asking for the volume of solution. Well I have the volume of the acetone. But I don't have the volume of the ethanol. And so I'm actually going to have to start the problem by figuring out the volume of ethanol, so that I know the volume of the solution. Because remember both of those things make up the solution. So if I have 15 grams of my ethanol, or ETOH as an abbreviation. And I'm going to use my density that's given, 0.789 grams per milliliter. Notice that I put the grams on the bottom so that grams and grams would cancel, and then I can find out that I have 19.0 milliliters of ethanol. So now I have the mass of my solute which was the ethanol, and I have the volume of the solvent, the acetone, as well as the volume of the solute, which is the ethanol. So I can find the volume of my solution. So I put in my mass which is 15.0 grams, over the 100 millilitres from the acetone plus the 19 millilitres, from the ethanol, and I multiply that by 100 and what I find is that the percentage is 12.6%, and I put it M/V, just to indicate that that is the percentage based on the mass volume percentage. We can find other percentages as well, but this is what this specific one is.