A square is transformed into a rectangle: Its length and breadth become 30% and 20% more than the original square’s side, respectively. By what percentage does the new rectangle’s area exceed the original square’s area?

Difficulty: Easy

Correct Answer: 56%

Explanation:


Introduction / Context:
We compare the area of a square with that of a rectangle formed by increasing the side in two perpendicular directions by different percentages. This is a standard compound-change area problem using multiplicative factors.


Given Data / Assumptions:
Square side = s. Rectangle length = 1.30s. Rectangle breadth = 1.20s.


Concept / Approach:
Original area = s^2. New area = (1.30s) * (1.20s) = 1.56 * s^2. The area therefore increases by a factor of 1.56 relative to the original, which corresponds to a 56% increase.


Step-by-Step Solution:

Original area = s * s = s^2 New area = (1.30s) * (1.20s) = 1.56 s^2 Increase % = (1.56 − 1) * 100 = 56%


Verification / Alternative check:
Assume s = 10 units; old area = 100. New area = 13 * 12 = 156. Excess = 56 over 100 ⇒ 56%.


Why Other Options Are Wrong:
36% and 50% mis-handle multiplicative compounding. 20% is far too small. 60% rounds up incorrectly.


Common Pitfalls:
Adding 30% + 20% and stopping at 50% without compounding. Always multiply the separate scale factors for perpendicular dimensions.


Final Answer:
56%

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