Chapter 13 - The Chemistry of Solutes and Solutions - Questions for Review and Thought - Topical Questions - Page 605c: 59c

Mass fraction= 0.144 Weight percent= 14.4%

Mass fraction of methanol= $\frac{mass\,of\, methanol}{mass\,of\, methanol+mass\,of\, ethanol}= \frac{15.0\,g}{15.0\,g+89.0\,g}$ $=0.144$ Weight percent= mass fraction$\times100\%$ $=0.144\times100\%=14.4\%$