From a container having pure milk, 10% is replaced by water and the process is repeated twice. At the end of the second operation, the milk is?  Choose the correct choice from the following options.
A) 50%
B) 60%
C) 55%
D) 75%
E) 81%
Let the total quantity of original milk = 1000gm   Milk after 1st operation = 90% of 1000 = 900gm   Milk after second operation = 90% of 900 = 810gm   Strength of final mixture = 81%   Answer is 81%
<result>E</result>
From a container having pure milk, 10% is replaced by water and the process is repeated twice. At the end of the second operation, the milk is?