A shopkeeper sells two items, A and B. Item B's cost price is twice as that of item A. The shopkeeper sells item A at 10% profit and item B at 20% profit. Which one of the following is the value of net profit?

To find the net profit percentage, we use the weighted average of the individual profits based on their cost prices. Let the cost price (CP) of item A be x. According to the problem, the CP of item B is 2x. The profit on item A is 10% of x (0.1x), and the profit on item B is 20% of 2x (0.4x). The total profit earned is the sum of these individual profits: 0.1x + 0.4x = 0.5x. The total cost price for both items is x + 2x = 3x. Net profit percentage is calculated as (Total Profit / Total CP) × 100. Substituting the values: (0.5x / 3x) × 100 = (1/6) × 100, which equals 16.66%. This method aligns with standard profit margin calculations where total revenue and total costs determine the final percentage.

Sources

1. [1] Microeconomics (NCERT class XII 2025 ed.) > Chapter 4: The Theory of the Firm under Perfect Competition > 4.3.3 Condition 3 > p. 58