A man buys oranges at 18 for a rupee and sells them at 12 for a rupee. Find the profit percentage.

Introduction:
Convert both buying and selling conditions to price per orange, then compute profit % using (SP − CP) / CP * 100.

Given Data / Assumptions:

• Buy: 18 for Rs 1 → CP per orange = Rs 1/18
• Sell: 12 for Rs 1 → SP per orange = Rs 1/12

Concept / Approach:
Profit % = ((1/12 − 1/18) / (1/18)) * 100.

Step-by-Step Solution:
SP − CP = 1/12 − 1/18 = (3 − 2)/36 = 1/36Profit % = (1/36) / (1/18) * 100 = (18/36) * 100 = 50%

Verification / Alternative check:
On 36 oranges: CP = 2 rupees, SP = 3 rupees; profit = 1 rupee → 50% of CP.

Why Other Options Are Wrong:
33.33%, 66.66%: Result from mis-scaling.None of these, 40%: Do not match calculation.

Common Pitfalls:
Using per-dozen math directly without converting to unit rates leads to mistakes.

Final Answer:
50 %