Question

In 135 litres of milk mixed with water the ratio of mild to water is 7:2 how much water should be added so that the ratio of milk to water becomes 5:2

Answer 1

amount of mixture = 135 l
ratio of milk and water = 7 : 2
amount of milk in mixture = 7/9 × 135 = 105l
ratio of milk and water in the new mixture = 5 : 2
part of milk in the new mixture = 5/7
let the amount of new mixture = x
since water is added so amount of milk is constant, therefore
5/7 × x = 105
5x = 105 × 7
x = (105 × 7)/5
x = 21 × 7
x = 147
so the amount of water added is
147 - 135 = 12 liters