Question

A container has capacity of 20 litres and is full of milk. 10 Litre of milk is taken out of it and replaced by same quantity of water again 10 litres of mixture is taken out and replaced by equal quantity of water. How much milk is left in the mixture.

1. 25 litres
2. 5 litres
3. 10 litres
4. 15 litres
5. None of these

Answer 1

Correct Answer - Option 2 : 5 litres

Given 

A container has capacity of 20 litres .

Formula used 

Milk left in container after n operations/Original quantity of milk in container

Calculation

Here, number of operations is 2, that is n = 2

Now,  Milk left in container after n operations/Original quantity of milk in container

⇒ ((20 – 10)/20)² × 20

⇒ (10/20)² × 20

⇒ 1/4 × 20 = 5 litre

∴ 5 litre of milk is left in the mixture.