Ratio of milk and water = 2 : 3 = 40 : 60 Given, 40% of the 2 : 3 solution of milk and water is replaced with water ⇒ Volume of milk removed = 40 × 40/100 = 16 ⇒ Volume of water removed = 40 × 60/100 = 24 ∴ new ratio of milk and water after removing 40% of solution = 24 : 36 New ratio of milk and water after adding 40% of water = 24 : 76 ∴ % reduction in concentration = (40 - 24)/40 = 40%