Comparing two selling prices: By selling a cellphone for ₹ 2,400, a shopkeeper makes a profit of 25%. If instead he sells it for ₹ 2,040, what would be his profit percentage?

Introduction / Context:
When you know one selling price and its profit%, you can recover the cost price and then evaluate the profit% at a second selling price on the same cost base.

Given Data / Assumptions:

• SP1 = ₹ 2,400 at 25% profit.
• Alternative SP2 = ₹ 2,040.

Concept / Approach:
CP = SP1 / 1.25. Profit% at SP2 = (SP2 − CP)/CP * 100.

Step-by-Step Solution:
CP = 2,400 / 1.25 = ₹ 1,920Profit at SP2 = 2,040 − 1,920 = ₹ 120Profit% = 120 / 1,920 * 100 = 6.25%

Verification / Alternative check:
Average SP per unit style checks are unnecessary here since cost is already known precisely from the first scenario.

Why Other Options Are Wrong:

• 10% / 15% / 6.5%: do not equal 120/1,920 * 100.

Common Pitfalls:

• Treating the 25% as of SP instead of CP when recovering cost.

Final Answer:
6.25 %