CAT 2021 Question Paper | Quant Slot 2

CAT 2021 Quant was dominated by Arithmetic followed by Algebra. In Arithmetic, the questions were dominated by topics like Speed-time-distance, Mixture and Alligations. This year, there was a surprise. The questions from Geometry were relatively on the lower side as compared to the previous years. There were 8 TITA Qs this year. Overall this section was at a medium level of difficulty.

Question 4 : From a container filled with milk, 9 litres of milk are drawn and replaced with water. Next, from the same container, 9 litres are drawn and again replaced with water. If the volumes of milk and water in the container are now in the ratio of 16 : 9, then the capacity of the container, in litres, is

Video Explanation

Explanatory Answer

Let’s assume the capacity of the container is ‘c’
Let’s track down the milk which is retained.
The milk retained after taking first 9 litres from the container is (c × \\frac{c - 9}{c}) ) 
The milk retained after taking next 9 litres from the container is ( c × \\frac{c - 9}{c}) × \\frac{c - 9}{c}) )
The volumes of milk and water in the container are now in the ratio of 16 : 9.
The milk in the container is \\frac{16}{25})
\\frac{c \times \frac{c - 9}{c} \times \frac{c - 9}{c}}{c}) = \\frac{16}{25})
(\\frac{c - 9}{c}) )² = \\frac{16}{25})
\\frac{c - 9}{c}) = \\frac{4}{5})
c = 45

The answer is '45'