How much milk to add to reduce water percentage

Step 1: Calculate the initial amount of water and milk

The initial mixture is 30 liters and contains 10% water.
Initial amount of water = 30 × (10/100) = 3 liters
Initial amount of milk = 30 - 3 = 27 liters

Step 2: Set up the equation for the new mixture

Let x be the amount of milk added.
New amount of milk = 27 + x liters
Amount of water remains the same = 3 liters
Total volume of the new mixture = 30 + x liters
New percentage of water = 2%

Equation: 3 = (2/100) × (30 + x)

Step 3: Solve for x

3 × 100 = 2 × (30 + x)
300 = 2 × (30 + x)
150 = 30 + x
x = 120 liters

Answer:

The amount of milk that should be added is (D) 120 litres.