Answer:
4:1
Step-by-step explanation:
Let us assume that the cost of water is free, that is Rs.0.
Let x represent the number of liters of milk, y represent the number of liters of water and z represent the volume of the mixture in liters, hence:
z = x + y (1)
Milk cost Rs.5 per liter, water cost Rs.0 per liter and the mixture cost Rs.4 per liter. Therefore:
5x + 0(y) = 4z (2)
Substituting z = x + y in equation 2 gives:
5x + 0(y) = 4(x + y)
5x = 4x + 4y
5x - 4x = 4y
x = 4y
x / y = 4 / 1
x : y = 4 : 1
The proportion in which the milk is to be mixed with water is 4 : 1, that is 4 liters of milk per 1 liter of water
