The density of a methanol-water solution that is 12.000 weight percent methanol is 0.97942...

The density of a methanol-water solution that is 12.000 weight percent methanol is 0.97942 g/cm3 at 15°C and 1 atm. For a solution that is 13.000 weight percent methanol, the density is 0.97799 g/cm3 at this T and P. Since the change in solution composition is small, we can estimate  by

Calculate for a methanol-water solution at 15°C and 1 atm that is CH3OH by weight. Then calculate for this solution.