When the price of a pressure cooker rises by 15%, sales fall by 15%. Determine the net percentage effect on total revenue (money receipt).

Introduction:
Total revenue equals price multiplied by quantity sold. When both change by given percentages, multiply the corresponding factors to get the net effect. The combined effect is not the simple difference of the percentages.

Given Data / Assumptions:

• Price increases by 15%: multiplier 1.15.
• Quantity decreases by 15%: multiplier 0.85.

Concept / Approach:
Revenue_new = Revenue_old * 1.15 * 0.85. Compare the product with 1 to obtain the overall percentage change.

Step-by-Step Solution:
Net multiplier = 1.15 * 0.85 = 0.9775Percentage change = (0.9775 - 1) * 100 = -2.25%

Verification / Alternative check:
Use Rs 100 revenue baseline. New revenue = 97.75, which is 2.25 less than 100, i.e., a 2.25% decrease. This matches the computed result.

Why Other Options Are Wrong:

• No effect: would require the product of multipliers to be 1, which it is not.
• 15% decrease: incorrectly subtracts percentages.
• 7.5% increase: sign and magnitude are both wrong.

Common Pitfalls:

• Adding +15 and -15 to conclude zero change.
• Applying the second percentage to the original base instead of the updated value.

Final Answer:
2.25% decrease