A vendor sold 25 laptops at a profit of 12% and 15 laptops at a profit of 20%. If he had sold all the 40 laptops at a profit of 18%, his profit would have increased by Rs. 30,000. What is the cost price of each laptop, if the cost price of all the 40 laptops is the same?

Explanation

Let the cost price of each laptop be Rs. x. Since there are 40 laptops, the total cost price of all laptops is 40x. According to the problem: 1. The profit on 25 laptops sold at a 12% profit = 25 × 12% × x = 25 × 0.12x = 3x 2. The profit on 15 laptops sold at a 20% profit = 15 × 20% × x = 15 × 0.20x = 3x Total actual profit = 3x + 3x = 6x If all 40 laptops had been sold at an 18% profit, the total profit would have been: 18% of 40x = 0.18 × 40x = 7.2x According to the problem, this hypothetical profit is Rs. 30,000 more than the actual profit: 7.2x - 6x = 30,000 1.2x = 30,000 x = 30,000 / 1.2 x = 25,000 Therefore, the cost price of each laptop is Rs. 25,000.