How much water should be added to 50 litre pure milk to gain 10% by selling at CP? क्रय मूल्य पर बेचने पर 10% का लाभ प्राप्त करने के लिए 50 ली. शुद्ध दूध में कितना पानी मिलाया जाना चाहिए?

When water is added to pure milk and sold at cost price, the profit percentage equals the percentage of water in the mixture. We need 10% profit, so water should be 10% of the milk quantity. For 50 liters of milk: 10% of 50 = 5 liters of water. After adding 5 liters water, total = 55 liters, and water fraction = 5/55 ≈ 9.09%, which gives approximately 10% profit when selling 55 liters at the price of 50 liters.