If the selling price of an item is 1,000 rupees after giving a discount of 20 percent on the marked price, then what was the original marked price of the item?

Introduction / Context:
This question is a straightforward application of percentage discount and reverse calculation of marked price from a known selling price. Such problems frequently appear in profit and loss sections of aptitude tests and help reinforce the relationship between marked price, discount, and selling price.

Given Data / Assumptions:
- Let the marked price be M rupees.
- A discount of 20 percent is offered on the marked price.
- The resulting selling price is 1,000 rupees.
- We need to find the value of M.

Concept / Approach:
A discount of 20 percent means the customer pays 80 percent of the marked price. Therefore the selling price equals 80 percent of M. We can express this as an equation, solve for M, and find the original marked price. Working with decimal factors is usually simpler than repeatedly manipulating percentages.

Step-by-Step Solution:
Step 1: After a 20 percent discount, the buyer pays 100 percent - 20 percent = 80 percent of M.Step 2: In decimal form, 80 percent = 0.8.Step 3: Therefore, selling price SP = 0.8 * M.Step 4: Given SP = 1,000 rupees, we have 0.8 * M = 1,000.Step 5: Solve for M: M = 1,000 / 0.8.Step 6: Compute 1,000 / 0.8 = 1,250 rupees.So, the marked price of the item was 1,250 rupees.

Verification / Alternative check:
Verify by applying the discount to the found marked price. Take 20 percent of 1,250, which is 0.2 * 1,250 = 250 rupees. Subtract this discount from the marked price: 1,250 - 250 = 1,000 rupees. This equals the given selling price, so the solution is consistent.

Why Other Options Are Wrong:
- 1,200 rupees and 1,400 rupees do not produce a selling price of exactly 1,000 rupees when reduced by 20 percent.
- 800 rupees is less than the selling price itself, which is impossible when a discount is applied; the selling price must always be less than or equal to the marked price in a normal discount situation.

Common Pitfalls:
A common mistake is to subtract 20 percent of 1,000 from 1,000, wrongly assuming the selling price is the base for the discount. The discount is always calculated on the marked price, not the final price. Another error is to treat 20 percent as 0.2 and add instead of subtract, or to forget to reverse the operation when solving for the original value. Always set up a clear equation that links selling price, discount percent, and marked price.

Final Answer:
The original marked price of the item was 1,250 rupees.