In a 120 litre mixture of milk and water, water is only 25%. The milkman sold 20 litres of this mixture and then he added 16.2 litres of pure milk and 3.8 litres of pure water in the remaining mixture. What is the percentage of water in the final mixture?

Mixture = 120 litre, Water = 25%

Quantity of water = $$\frac{25}{100} \times 120 = 30$$ litre

And milk = 120 - 30 = 90 litre

After selling 20 litre of mixture, remaining mixture = 100 litre

In 100 litre of mixture, amount of milk and water will remain in the same percent.

Water = $$\frac{25}{100} \times 100 = 25$$ litre

And milk = 100 - 25 = 75 litre

Now, he added 16.2 litre of milk and 3.8 litre of water.

Milk = 75 + 16.2 = 91.2 litre

And water = 25 + 3.8 = 28.8 litre

Total new mixture = 120 litre

$$\therefore$$ Required % = $$\frac{28.8}{120} \times 100 = 24 \%$$