Correct Answer - Option 1 : Rs. 480
Given
Selling Price of watch with a loss of 15% = 340 Rs.
Formula
Profit = Selling price – Cost price
Calculation
Selling price = 100% - 15% = 85%
⇒ 85% = 340
⇒ 120% = x
⇒ x = [(120 × 340)/85]
⇒ x = 24 × 20
⇒ x = 480 Rs.
∴ To gain 20% shopkeeper need to sell watch to Rs. 480