Question

A vessel has 500 litres of milk. 50 litres of milk is replaced with 50 litres of water in this vessel. If this operation is repeated another 2 more times, what is the percentage of milk in the vessel at the end?

A.
70.0
B.
72.9
C.
80.0
D.
81.0

Accepted Answer

B. Total operations $n = 3$. Remaining milk fraction = $\left(1 - \frac{50}{500}\right)^3 = \left(\frac{9}{10}\right)^3 = 0.729$. In percentage, milk remaining = $72.9\%$.

Successive Replacement of Liquid

Explanation

Practise this under exam conditions