A watch is sold at a loss of 10%. If it had been sold for Rs. 90 more, there would have been a gain of 5%. The cost price of the watch is
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Rs. 600
Let the cost price be Rs. \(x\). Moving from a 10% loss to a 5% gain raises the selling price by 15% of the cost price.
\(\text{First selling price} = 0.90x\)
\(\text{Second selling price} = 1.05x\)
\(1.05x - 0.90x = 90\)
\(0.15x = 90\)
\(x = 600\)
Check: \(0.90 \times 600 = 540\) and \(1.05 \times 600 = 630\), which differ by 90.
So the cost price is Rs. 600.