A 729 ml mixture contains milk and water in the ratio 7:2. How much more water should be added to get a new mixture with milk and water in the ratio 7:3?

A81 ml ✓ Correct

B90 ml

C85 ml

D75 ml

Correct answer: (A) 81 ml

Explanation

Add 81 ml of water.

milk = 729 x 7/9 = 567, water = 729 x 2/9 = 162.

milk stays 567 for the ratio 7 : 3.

new water = 567 x 3/7 = 243.

water to add = 243 - 162 = 81 ml.

Want more like this? Create a free account to practise a full test, track your progress, and get spaced-repetition review.