From a container having pure milk, 20% is replaced by water and the process is repeated thrice. At the end of the third operation, the milk is :

A. 40% pure

B. 50% pure

C. 51.2% pure

D. 58.8% pure

Answer: Option C

Solution(By Examveda Team)

Let total quantity of original milk = 1000 gm
Milk after first operation = 80% of 1000 = 800 gm
Milk after second operation = 80% of 800 = 640 gm
Milk after third operation = 80% of 640 = 512 gm
∴ Strength of final mixture = 51.2%