In a mixture, water and milk are in the ratio of 2 : 3. What is the amount of water that is to be added to 20 kg of this mixture to make the ratio of water and milk in the new mixture 1 : 1 ?

4 kg

Initial Mixture,

 Milk : Water

   3   :   2,

Final Mixture 

 Milk : Water 

  1    :   1

⇒ Making ratio of Milk in both solutions same, we multiply final solution with 3,

⇒ (1 : 1) x 3 = 3 : 3,

⇒ Quantity of initial mixture = 20 Kg,

⇒ (2 + 3)x = 20

⇒ 5x = 20,

⇒ x = 4 Kg,

Initial Mixture,

 Milk = 3 x 4 = 12 Kg, Water = 2 x 4 = 8 Kg 

⇒ Amount of water added to make ratio 1 : 1,

⇒ Milk = Water,

⇒ 12 = 8 + x

⇒ x = 12 - 8

⇒ x = 4 Kg

Hence, The amount of water that is to be added to make ratio of Milk and Water 1 : 1 is 4 Kg.