8 litres are drawn from a cask filled with wine and is then filled with water. This operation is performed three more times. The ratio of the quantity of wine now left in cask to that of the total solution is 16 : 81. How much wine did the cask hold originally?

8 litres are drawn from a cask filled with wine and is then filled with water. This operation is performed three more times. The ratio of the quantity of wine now left in cask to that of the total solution is 16 : 81. How much wine did the cask hold originally? Correct Answer 24 litres

Let the quantity of the wine in the cask originally be x litres.Using formula: Final Amount of solute that is not replaced =Initial Amount × $${\left( {\frac{{{\text{Vol}}{\text{. after removal}}}}{{{\text{Vol}}{\text{. after replacing}}}}} \right)^{\text{N}}}$$Where N = No. of operation done.Then ratio of wine to total solution in cask after 4 operations,$$\eqalign{ & 1 \times { {\left( {\frac{{x - 8}}{x}} \right)} ^4} = \frac{{16}}{{81}} \cr & \Rightarrow 1 \times {\left\{ {\frac{{ {x - 8} }}{x}} \right\}^4} = {\left( {\frac{2}{3}} \right)^4} \cr & \Rightarrow \frac{{ {x - 8} }}{x} = \frac{2}{3} \cr & \Rightarrow 3x - 24 = 2x \cr & \Rightarrow x = 24\,{\text{litres}} \cr} $$

Related Questions

The question given below consists of a statement and/or a question and two statements numbered l and ll given below it. You have to decide whether the data provided in the statement(s) is sufficient to answer the question. What is the quantity of the milk in 120 litres of a mixture of milk and water? l. If 12 litres of water is added to the mixture, then the ratio of the quantity of milk to that of the water would be 8 : 3 ll. 20 litres of the solution is taken out and replaced with pure milk, then the ratio of the quantity of milk to that of water in the solution would be 5 : 1.