Question

Surdeep bought a machinery for ₹ 800 after a $20\%$ discount on the company price. He fixes the selling price to earn $10\%$ profit on the original company price. Find the selling price. 

• A. ₹900
• B. ₹1000
• C. ₹1100
• D. ₹1200

Hint:

Work with the base price. Undo discounts first, then apply profit or loss on that same base if asked.

Answer 1

The Correct Option is C

Let company price be $P$. Given $0.8P=800 \Rightarrow P=1000$.
Required SP $= P \times (1+0.10) = 1000 \times 1.10 = \boxed{₹1100}$.

Answer 2

Instead of writing and solving an equation for the company price, we can use the unitary method to find it directly, then check each option for the selling price.

1. Option A (₹900): If the ₹\(800\) paid corresponds to \(80\%\) of the company price (after a \(20\%\) discount), then \(1\%\) of the company price is \(\dfrac{800}{80}=₹10\), so the full company price is \(100\times 10=₹1000\). A required selling price giving \(10\%\) profit on ₹\(1000\) is \(1000+100=₹1100\), not ₹900, so this option is incorrect.
2. Option B (₹1000): This is the company price itself, not the required selling price (which includes the \(10\%\) profit), so it is incorrect.
3. Option C (₹1100): As found above, \(1\%\) of company price \(=₹10\), so company price \(=₹1000\), and the selling price for a \(10\%\) profit on this is \(1000+10\%\text{ of }1000=1000+100=₹1100\). This matches.
4. Option D (₹1200): This would require a company price of about ₹\(1091\), which does not match the unitary-method value of ₹\(1000\), so it is incorrect.

Using the unitary method to find \(1\%\) of the company price directly gives the same company price of ₹1000, and hence the same required selling price.

Hence, the correct answer is option C: ₹1100.