A vessel contains 60 liters of milk.  12 liters of milk taken out  from it and replaced with water.  Then again from mixture 12 liters is taken out and replaced with water.  The ratio of milk and water in the resultant mixture is:

16 : 9

Total Milk = 60 liters

drawn off = 12 liters (two times)

(1 - \(\frac{x}{a}\))^t

x = replaced quantity

a = capacity

t = number of process

Therefore,

⇒ (1 - \(\frac{12}{60}\))ⁿ = \(\frac{4}{5}\)ⁿ = \(\frac{16}{25}\)  (where 16 → milk and 25 → total quantity)

Hence, Water now = 25 - 16 = 9

⇒ M  :  W = 16 :  9