In a 20 litre mixture ratio of milk and water is 3:1.how much milk should added so that mixture ratio Become 4:1?  Select the correct option:
A) 3 B) 2 C) 8 D) 6 E) 5

Rationale: amount of milk = 20 × 3 / 4 = 15 litre and water = 5 litre let x litre milk to be added then 15 + x / 5 = 4 / 1 = 15 + x = 20 , x = 5 answer e
Answer: E