Discount and marked price: A watch is sold with a 5% discount. If the shopkeeper instead gives a 6% discount, his profit decreases by ₹15. What is the marked price (list price) of the watch?

Introduction / Context:
This problem tests the link between discount percentage and selling price. A 1% extra discount reduces the selling price by exactly 1% of the marked price, which directly shows up as a reduction in profit (since cost price is unchanged).

Given Data / Assumptions:

• Discount changes from 5% to 6%.
• Profit decreases by ₹15 when discount increases by 1%.
• Marked price = MP, cost price = CP (constant).

Concept / Approach:
With MP fixed, selling price SP = MP*(1 − discount). If discount rises by 1%, SP falls by 0.01*MP. Because CP is constant, the decrease in profit equals the decrease in SP, which equals 0.01*MP. Hence 0.01*MP is directly the given ₹15 drop.

Step-by-Step Solution:

Verification / Alternative check:
If MP = 1500, SP at 5% is 1500*0.95 = 1425; SP at 6% is 1500*0.94 = 1410; difference = ₹15, matching the statement.

Why Other Options Are Wrong:
Values like ₹1250, ₹1400, ₹750, ₹1600 would not make a 1% of MP equal ₹15; their 1% differs from ₹15.

Common Pitfalls:
Confusing profit percent with discount percent; here only the SP change matters since CP is unchanged.

Final Answer:
₹ 1500