CAT 2023 Slot 2 QA Question 16: A container has 40 liters of milk. Then, 4 liters are removed from the container and replaced with 4 liters of water. This process of replacing 4 liters of the liquid in the container with an equal vo

Question

A container has 40 liters of milk. Then, 4 liters are removed from the container and replaced with 4 liters of water. This process of replacing 4 liters of the liquid in the container with an equal vo

Accepted Answer

In each operation, 4 liters out of 40 liters are removed. So, 10% of the current milk is removed each time.

Hence, after $t$ operations, the amount of milk left is:
$40(1 - \dfrac{4}{40})^{t} = 40(0.9)^{t}$

Milk becomes less than water when the milk is less than 20 liters.
$40(0.9)^{t} 
$(0.9)^{t}