A trader sells goods at the cost price but uses a 960 g weight in place of a 1 kg weight. What is the gain percentage?

💡 Solution & Explanation

The buyer pays for 1,000 g but receives only 960 g. So the seller gains 40 g on every 960 g actually given. Gain % = (40 ÷ 960) × 100 = 4.17%. Dividing by 1,000 instead gives 4%, which is wrong because the cost is for the 960 g handed over.