A shopkeeper sells rice at cost price but uses a 900 g weight instead of 1 kg. What is his profit percentage?
11.11% (11 1/9 %). He charges for 1,000 g but hands over 900 g, gaining 100 g on every 900 g he actually gives. Profit % = 100/900 x 100 = 11.11%.
Explain it simply
The customer pays for a full kilo, so the shopkeeper's selling price is the price of 1,000 g. What he actually spends is the cost of 900 g. His profit is the price of the missing 100 g. Profit percentage is always measured on cost, and his cost is the 900 g he handed over, not the 1,000 g he charged for.
Example
Question: Cost price = selling price, but the weight used is 900 g for 1 kg. Find the profit %.
- Let cost of rice = ₹1 per gram.
- Customer pays for 1,000 g: SP = ₹1,000.
- Shopkeeper gives 900 g: CP = ₹900.
- Profit = ₹100. Profit % = 100 / 900 x 100 = 11.11%.
Formula: profit % = (true weight - false weight) / false weight x 100 = 100 / 900 x 100.
If he also adds a 10% markup on price, multiply the factors: 1.1 x (1000/900) = 1.2222, a profit of 22.22%.
console.log(((1000 - 900) / 900 * 100).toFixed(2)); // Output: 11.11
console.log(((1.1 * 1000 / 900 - 1) * 100).toFixed(2)); // Output: 22.22What to say in the interview
"He is paid for 1,000 grams but his cost is 900 grams, so he gains 100 on 900, which is 11 and one ninth percent. Profit is always taken on what he actually spends."
Common mistakes
- Dividing by 1,000 and answering 10%.
- Adding percentages (10% markup + 11.11%) instead of multiplying factors when two tricks combine.