A milkman claims to sell milk at its cost price, still, he is making a profit of 30% since he has mixed some amount of water in the milk. What is the % of milk in the mixture?

The milkman sells the milk at cost price but makes a profit of 30%.

This is possible only because he is mixing water (which is free) with milk.

Let us assume:

• Cost price of 1 litre of pure milk = Rs. 100
• He mixes water and makes a 1-litre mixture and still sells it at Rs. 100

Since he makes 30% profit:

⇒ Cost price of 1 litre of mixture = 100 / 1.30 ≈ Rs. 76.92

This means, the milk in the mixture is worth Rs. 76.92 and the remaining part (100 - 76.92 = Rs. 23.08) is water.

Calculate the % of milk in the mixture:

(76.92 / 100) × 100 = 76.92%

Answer: The percentage of milk in the mixture is approximately 76.92%.