A trader sells goods at the cost price but uses an 800 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 800 g. So the seller gains 200 g on every 800 g actually given. Gain % = (200 ÷ 800) × 100 = 25%. Dividing by 1,000 instead gives 20%, which is wrong because the cost is for the 800 g handed over.