A vessel contains 56 litres of mixture of milk and water in the ratio 5 : 2. How much water should be mixed with it so that the milk to water ratio becomes 4 : 5.

34 litres

The correct answer is Option (3) → 34 litres

Ratio of Milk to water in original 56 litres mixture = 5 : 2

Milk = $\frac{5}{7}×56=40$

Water = 16

Let x be litres of water to be added

$\frac{40}{x+6}=\frac{4}{5}$

$200=4x+64$

$136=4x$

$x=34$