In a mixture of 60 litres, the ratio (by volume) of milk and water is 2 : 1. If X litres of water is added in the mixture, the ratio of milk and water becomes 1 : 2, then what is the value of X?

60

Initial solution,

Milk : Water

 2    :   1

After adding X liters water, Final solution,

 Milk : Water

  1    :   2

⇒ Making ratio of milk in both the solution same, we multiply final ratio with 2,

⇒ (1 : 2) x 2 = 2 : 4,

⇒ Difference between Final ratio of water and Initial ratio of water = 4 - 1 = 3 units,

⇒ Total quantity of initial solution = 60 liters,

⇒ (2 + 1) units = 60

⇒ 3 units = 60

⇒ 1 unit = 20 L,

⇒ Therefore, water added to to initial solution i;e; is = 3 x 20 = 60 liters.