The length and breadth of a rectangle are changed by +30% and −20%…
2021
The length and breadth of a rectangle are changed by +30% and −20% respectively. What is the percentage change in the area of the rectangle?
Answer: D. +4% — Let the original length be L and breadth be B. The original area is A = L × B. The length increases by 30%, so the new length is 1.30L. The breadth decreases…
- A.
−6%
- B.
+6%
- C.
−4%
- D.
+4%
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Correct answer: D
Let the original length be L and breadth be B. The original area is A = L × B.
The length increases by 30%, so the new length is 1.30L.
The breadth decreases by 20%, so the new breadth is 0.80B.
The new area is calculated as (1.30L) × (0.80B) = 1.04LB.
Comparing the new area to the original: 1.04LB - LB = 0.04LB.
The percentage change is (0.04LB / LB) × 100% = +4%.
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