The list price of an article is Rs 900. It is sold after two successive discounts of 20% and 10%. What is the final selling price of the article?

Introduction / Context:
This question again illustrates successive discounts, but with concrete rupee values. Instead of calculating a single equivalent discount rate, we directly find the final selling price after applying each discount step by step. These situations commonly occur during festive sales or clearance offers, and they are also popular in quantitative aptitude tests to check clarity on repeated percentage reductions.

Given Data / Assumptions:

• List price or marked price of the article = Rs 900.
• First discount offered = 20% on the list price.
• Second discount offered = 10% on the already reduced price.
• We need to find the final selling price after both discounts.

Concept / Approach:
First, we reduce the marked price by 20% to get an intermediate price. Then we reduce that intermediate price by 10% to get the final selling price. Each discount applies to the price obtained after the previous discount, not to the original list price. The process can also be represented by multiplying by remaining fractions: first 0.8 for 20% discount, then 0.9 for 10% discount, giving an overall factor of 0.72 on the list price.

Step-by-Step Solution:
Step 1: Initial list price = Rs 900. Step 2: First discount = 20%, so price after first discount = 900 * (1 − 20/100) = 900 * 0.8. Step 3: Compute intermediate price: 900 * 0.8 = 720. Step 4: Second discount = 10% on 720, so final price = 720 * (1 − 10/100) = 720 * 0.9. Step 5: Compute final selling price: 720 * 0.9 = 648. Step 6: Therefore, the final selling price is Rs 648.

Verification / Alternative check:
Combine both discounts as a single factor first. Remaining fraction after 20% discount is 0.8 and after 10% discount is 0.9. Net factor = 0.8 * 0.9 = 0.72. Applying this directly to the list price: SP = 900 * 0.72 = 648. This matches the stepwise calculation and confirms the correctness of the answer.

Why Other Options Are Wrong:

• Rs 640 and Rs 548 come from incorrect calculations or wrong multipliers.
• Rs 540 would be correct only if the overall remaining factor were 0.6 instead of 0.72, which would correspond to different discounts.

Common Pitfalls:
Some candidates mistakenly deduct the second discount from the original list price instead of the discounted price, effectively treating both discounts as independent on the same base. Others wrongly add discounts as 20% + 10% = 30% and then compute 900 * 0.7 = 630, which is incorrect since successive discounts compound multiplicatively. Keeping track of which price each discount applies to helps avoid these errors.

Final Answer:
The final selling price of the article is Rs 648.