Q. In a 30 litre mixture of milk and water, the ratio of milk and water is 7:3. How much water should be added in the mixture so that the ratio of milk and water becomes 3:7?

A) 5

B) 12

C) 28

D) 40

✔ 40

Additional Information > Exam point of View

In 30 Lt. milk and water ratio is 7:3

Total Ratio=7+3=10

so Milk= (7x30)/10= 21 Lt.

Water : (3x30)/10 = 9 Lt.

Let Y amount of water added to mixture

→ 21:(Y+9)=3:7 

→ 21x7=3Y+27 

→ 147-27 = 3Y

→ 120 = 3Y

→ Y=120/3 = 40 Lt.