A TV’s price is reduced by 30% and sales increase by 20%. What is the overall percentage change in revenue (price × quantity)?

Difficulty: Easy

Correct Answer: 16% decrease

Explanation:


Introduction / Context:
Revenue is the product of price and quantity sold. When both factors change, multiply the respective percentage multipliers to get the combined effect, and then translate back into a percentage change.


Given Data / Assumptions:

  • Price change: −30% ⇒ multiplier 0.70.
  • Quantity change: +20% ⇒ multiplier 1.20.
  • Initial revenue serves as 100% reference.


Concept / Approach:
New revenue factor = 0.70 * 1.20 = 0.84. That is 84% of the original, hence a 16% decrease overall.


Step-by-Step Solution:

Compute product of multipliers: 0.70 × 1.20 = 0.84.Interpretation: revenue is 84% of original.Change = 100% − 84% = 16% decrease.


Verification / Alternative check:
If original price = ₹100 and sales = 100 units ⇒ revenue = ₹10,000. New price = ₹70; new sales = 120 units; new revenue = ₹8400 ⇒ 16% down.


Why Other Options Are Wrong:
A 10% change comes from adding or subtracting percentages instead of multiplying; “16% increased” flips the sign.


Common Pitfalls:
Adding −30% and +20% to get −10% (wrong). Effects on different factors must be multiplied.


Final Answer:
16% decrease

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