Answer:
18.6% by mass MtOH
Step-by-step explanation:
Solution composition = 200ml MtOH + 693.1 ml H₂O
= (200ml MtOH)(0.792g MtOH/ml MtOH) + (693.1 ml H₂O)(1.000g H₂O/ 1 ml H₂O)
= 158.4 g MtOH + 693.1 g H₂O = 851.5 g
mass% MtOH = (158.4g MtOH/851.5g Solution) x 100% = 18.6% by mass MtOH