Question

10$\%$ water is present in 40 litres of a mixture of milk and water. How much water must be added to it so as to get 20$\%$ water in the new mixture?

• A. 25L
• B. 20L
• C. 15L
• D. 10L
• E. 5L

Answer 1

The correct option is E

5L

The existing mixture has 10$\%$ water. Water is to be added, so the other solution has 100$\%$ water. So by alligation method:

The two mixture should be added in the ratio 8 $:$ 1.

i.e. for every 8 litres of first mixture, 1 litre of water should be added.

$\text{Therefore for 40 litres of first mixture}\frac{40}{8}\times 1=5\text{litres of water should be added.}$