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 Choose the correct option:
A) 40% pure B) 50% pure C) 51.2% pure D) 58.8% pure E) None
Solution   Let total quantity of original milk = 100 gm.   Milk after first operation = 80% of 1000   ‹=› 800gm.   Milk after second operation = 80% of 800   ‹=› 640gm.   Milk after third operation = 80% of 640   ‹=› 512gm.   Strength of final mixtures = 51.2%.   Answer 51.2% pure
<result>C</result>
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