A container contains 100 liters of milk. From this container, 10 liters of milk is taken out and replaced by water. This process is repeated two more times. The amount of milk left in the container now is:

72.9 liters

The correct answer is Option (4) → 72.9 liters

Total volume of container = 100 liters

Milk taken out each time = 10 liters

Fraction of milk left after each operation = $\frac{100-10}{100}=\frac{90}{100}=\frac{9}{10}$

After 3 repetitions, amount of milk left = $100\left(\frac{9}{10}\right)^3$

$=100\cdot\frac{729}{1000}$

$=72.9$ liters

Milk left = 72.9 liters