How do you solve profit and loss questions in aptitude tests?

The most common mistake in these questions is calculating the percentage against the wrong base — profit and loss percentages are always relative to the cost price, not the selling price.

A worked example

Question: A vendor buys a bicycle for ₹4,000 and sells it for ₹4,600. What is the profit percentage?

Solution: Profit = 4,600 − 4,000 = ₹600. Profit % = (600 ÷ 4,000) × 100 = 15%.

Working backward from the selling price

Question: A shopkeeper sells a item for ₹690 at a 15% profit. What was the cost price?

Solution: If CP + 15% of CP = 690, then 1.15 × CP = 690, so CP = 690 ÷ 1.15 = ₹600.

Key formulas

• Profit = SP − CP (when SP > CP)
• Loss = CP − SP (when CP > SP)
• Profit % = (Profit ÷ CP) × 100
• Loss % = (Loss ÷ CP) × 100