Question

In 120 litres of a mixture of milk and water, water is only 25%. The milkman sold 20 litres of this mixture and then he added 16.2 litres of pure milk and 3.8 litres of pure water to the remaining mixture. What is the percentage of water in the final mixture?

1. 35%
2. 25%
3. 18%
4. 24%
5. 10%

Answer 1

Correct Answer - Option 4 : 24%

Given:

The total mixture is 120 litres. 

In a mixture of milk and water, water is 25%.

Added quantity in the mixture is 16.2 litres of pure milk and 3.8 litres of pure water.

Concept Used:

New quantity of Water/New quantity of Milk = (Quantity of Water + Quantity of Added Water)/(Quantity of Milk + Quantity of Added Milk)

Calculation:

Quantity of water in original mixture = 120 × 25/100 = 30 litres

And quantity of milk in original mixture = 120 – 30 = 90 litres

Now, milkman sold 20 L of mixture,

So, remaining mixture = 120 – 20 = 100 litres

Quantity of water in 100 L mixture = 100 × 25/100 = 25 litres

And, Quantity of milk in 100 L mixture = 100 – 25 L = 75 litres

Quantity of milk in new mixture = 75 + 16.2 = 91.2 litres

And Quantity of water in new mixture = 25 + 3.8 = 28.8 litres

Now, percentage of water in new mixture

⇒ 28.8 × 100/(91.2 + 28.8)%

⇒ 2880/120%

⇒ 288/12% = 24%

∴ The percentage of water in the final mixture is 24%.