Ratio of water and milk in a container is 2 : 3. If 40 liter mixture removed from the container and same quantity of milk is added to it then the ratio of water to milk becomes 1 : 4. Find the initial quantity of mixture?

• Let the initial quantity of the mixture be x liters.
• Water = (2/5) × x = 0.4x
• Milk = (3/5) × x = 0.6x

After removing 40 liters of mixture:

• Water removed = (2/5) × 40 = 16 liters
• Milk removed = (3/5) × 40 = 24 liters

Remaining:

• Water = 0.4x – 16
• Milk = 0.6x – 24

Then, 40 liters of milk is added:

• New milk = (0.6x – 24) + 40 = 0.6x + 16

New water : milk = 1 : 4

So we form the equation:

(0.4x – 16) / (0.6x + 16) = 1 / 4

Cross-multiplying:

4(0.4x – 16) = 0.6x + 16
1.6x – 64 = 0.6x + 16
1.6x – 0.6x = 16 + 64
1x = 80

Answer: 80 liters

The initial quantity of the mixture was 80 liters.