If one saree is offered free on the purchase of three sarees at the same marked price, what is the effective discount percentage on each saree?

Introduction / Context:
Shops often use "buy one, get one free" type offers instead of directly saying a percentage discount. This question asks you to translate an offer of one free saree on the purchase of three sarees into an equivalent percentage discount on each saree. Understanding this helps in comparing different promotional schemes in real life and in exams.

Given Data / Assumptions:
- All sarees have the same marked price; call it P rupees per saree.
- The customer buys 3 sarees and gets 1 saree free.
- Total sarees received = 4.
- Total amount paid = price of 3 sarees = 3P.
- We want the effective discount percentage compared to paying full price for all 4 sarees.

Concept / Approach:
If there were no offer, the customer would pay full price for all 4 sarees, that is 4P rupees. With the offer, the customer still receives 4 sarees but pays only 3P rupees. The difference 4P - 3P equals the discount amount. The effective discount percentage is then the discount divided by the original full price, multiplied by 100.

Step-by-Step Solution:
Step 1: Full price without offer for 4 sarees = 4P rupees.Step 2: Price actually paid with the offer = 3P rupees.Step 3: Discount amount = 4P - 3P = P rupees.Step 4: Effective discount percentage = (Discount / Full price) * 100.Step 5: Substitute values: Effective discount percentage = (P / 4P) * 100.Step 6: Simplify P / 4P = 1 / 4.Step 7: Therefore, effective discount percentage = (1 / 4) * 100 = 25 percent.

Verification / Alternative check:
Assume a numerical value for P, say P = 100 rupees. Then without offer, 4 sarees would cost 400 rupees. With the offer, you pay 300 rupees for 4 sarees. The discount is 100 rupees. Discount percentage = (100 / 400) * 100 = 25 percent. This agrees with the general algebraic solution.

Why Other Options Are Wrong:
- 20 percent and 30 percent do not match the exact ratio of 1 free out of 4 total sarees.
- 40 percent would mean a much larger price reduction; that would correspond to paying only 60 percent of the total, which is not the case here since the customer pays 3 out of 4 parts, that is 75 percent of the total.

Common Pitfalls:
Some learners mistakenly compute the discount as 1 out of 3 and say 33.33 percent, forgetting that the correct base is the total value of 4 sarees, not just the paid ones. Always compare the discount value to the full price of the goods received. Thinking in terms of "total cost without offer" versus "actual cost with offer" usually clarifies the correct base for the percentage calculation.

Final Answer:
The effective discount on each saree is 25 percent.