A trader sells wire and earns a profit of 60% on the cost price. What is the profit percentage when calculated on the selling price?

Introduction / Context:
This question distinguishes between profit percentage calculated on cost price and profit percentage calculated on selling price. Typically in aptitude questions, profit and loss percentages are defined with respect to cost price. Here, however, you are asked to convert a known profit percentage on cost into an equivalent percentage on selling price. This is an important conceptual twist and is frequently tested in exams.

Given Data / Assumptions:
- Profit on cost price is 60%. - Profit percentage is defined normally as Profit divided by cost price times 100. - We must find profit expressed as a percentage of selling price instead. - No additional charges or discounts are mentioned.

Concept / Approach:
Let the cost price be C. A 60% profit means Profit = 0.60 * C, so Selling Price S = C + 0.60 * C = 1.60 * C. If we want profit percentage on selling price, we compute Profit / S * 100. Since both profit and selling price are expressed in terms of C, the cost price cancels and the result becomes a simple fraction.

Step-by-Step Solution:
Step 1: Let cost price be C. Step 2: Profit on cost price = 60% of C = 0.60 * C. Step 3: Selling price S = C + 0.60 * C = 1.60 * C. Step 4: Profit percentage on selling price = (Profit / S) * 100. Step 5: Substitute Profit = 0.60 * C and S = 1.60 * C. Step 6: Profit percentage on selling price = (0.60 * C / 1.60 * C) * 100. Step 7: The cost price C cancels, leaving (0.60 / 1.60) * 100. Step 8: 0.60 / 1.60 = 3 / 8 = 0.375. Step 9: Therefore, profit percentage on selling price = 0.375 * 100 = 37.5%.

Verification / Alternative check:
Choose a simple cost price for verification. Let C = Rs. 100. A 60% profit gives Profit = Rs. 60 and S = Rs. 160. Then profit percentage on selling price is 60 / 160 * 100 = 37.5%. This numerical check agrees perfectly with the algebraic result, confirming that the conversion has been done correctly.

Why Other Options Are Wrong:
33.33% would arise if the ratio were one third, which is not the case here. 40% and 60% are simply reinterpretations of the given data without doing the necessary transformation. 60% is the profit percentage on cost price, not on selling price. Only 37.5% matches the correct ratio between profit and selling price when profit on cost price is 60%.

Common Pitfalls:
One pitfall is to assume that profit percentage on selling price is the same as on cost price. Another is to try to subtract or add percentages without working through the underlying values. The safest approach is to assign a variable (or assume a simple number) for cost price, compute profit and selling price, and then calculate the desired percentage from first principles.

Final Answer:
The profit percentage calculated on the selling price is 37.5%.