**Q13. Milk and water in a solution of 56 ml is such that after replacing 16 ml of the solution and adding 5 ml of water, the milk and water ratio is 5 **∶ **4. What was the concentration of milk in the mixture initially? **

Solution:

Quantity of Solution = 56 ml (Given)

16 ml of the solution replaced with 5 ml of water

then the solution quantity will be = (56 – 16) + 5 = 45 ml

Milk : Water = 5 : 4

M + W = 45 (will have to be distributed in the ratio of 5 : 4) In the Final Mixture,

Milk = 25 ml, Water = 20 ml

In 20 ml Water, 5 litre was added after replacement.

∴ Before Replacement, Water = 20 - 5 = 15 ml

Ratio of Milk and Water (Initially) = 25 : 15 = 5 : 3

16 ml of solution was replaced (will be calculated in the ratio of 5 : 3) Replaced Quantity of Milk and Water = 10 ml and 6 ml

Hence, Initial Quantity of Milk = 25 ml + 10 ml = 35 ml