Two vessels contain milk and water in the ratios 7 : 8 and 13 : 5. If the contents of the two vessels are mixed in the ratio 2 : 1, find the ratio of milk to water in the new mixture.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 149 : 121
The ratio totals are 15 and 18, so take a volume both divide into: 180 litres from the first vessel and 90 litres from the second keeps the ratio 2 : 1 and gives whole numbers.
First vessel, 180 litres: milk \(\displaystyle =\frac{7}{15}\times180=84\), water \(=96\)
Second vessel, 90 litres: milk \(\displaystyle =\frac{13}{18}\times90=65\), water \(=25\)
Milk \(=84+65=149\), water \(=96+25=121\)
The new mixture has milk and water in the ratio 149 : 121.