A website is selling a smartphone at a discounted price of Rs 18,000, while the marked price printed on the phone is Rs 25,000. At what discount percentage on the marked price is the smartphone being sold?

Introduction / Context:
This question is a straightforward application of the discount formula, where the marked price and the selling price are given. You are required to determine the percentage discount offered on the marked price of the smartphone.

Given Data / Assumptions:

• Marked price of smartphone = Rs 25,000.
• Selling price after discount = Rs 18,000.
• Discount percent on marked price = unknown.
• No additional taxes or extra discounts are mentioned.

Concept / Approach:
Discount amount is the difference between marked price and selling price: Discount = Marked price - Selling price. Discount percent is calculated with respect to the marked price, using: Discount percent = (Discount / Marked price) * 100. Substituting the given values will directly give the required percentage.

Step-by-Step Solution:
Step 1: Marked price = Rs 25,000. Step 2: Selling price = Rs 18,000. Step 3: Discount amount = 25,000 - 18,000 = Rs 7,000. Step 4: Discount percent = (7,000 / 25,000) * 100. Step 5: Simplify the fraction 7,000 / 25,000 = 7 / 25. Step 6: Compute (7 / 25) * 100 = 28 percent.

Verification / Alternative check:
If the discount is 28 percent on Rs 25,000, the discount amount = 25,000 * 28/100 = 25,000 * 0.28 = Rs 7,000. Selling price = 25,000 - 7,000 = Rs 18,000, which matches the given selling price. This confirms that the calculated discount rate is correct.

Why Other Options Are Wrong:
22 percent and 20 percent: These are much lower than required; they produce smaller discount amounts that do not reduce the price to Rs 18,000. 25 percent: This would give a discount of 6,250, resulting in a selling price of 18,750, not 18,000. 30 percent: This would give a discount of 7,500 and would reduce the price to 17,500, which is lower than the given selling price.

Common Pitfalls:
Students sometimes mistakenly compute discount percent based on the selling price instead of the marked price. Another common mistake is to mix up the direction of change and compute percentage increase instead of discount. Always remember that discount percent is calculated on the marked price, because that is the original reference value before any reduction.

Final Answer:
The smartphone is being sold at a discount of 28 percent on the marked price.