A container contains 40 liters of milk, From this container 4 liters of milk was taken out and replaced by water. This process was repeated further 2 times. How much milk is now contained by the container?  Choose one: A) 25.5 liters B) 29.16 liters C) 30.98 liters D) 42.15 liters E) 48.32 liters

Rationale: "amount of milk left after 3 operations = 40 ( 1 - 4 / 40 ) ^ 3 = 40 * 9 / 10 * 9 / 10 * 9 / 10 = 29.16 liters answer is b"
Answer: B