Multiple choice

The area of the rectangle is (400 m^2). Both length and breadth are increased by 10%. The total increase of the area in percentage is equal to?

  1. 22%

  2. 21%

  3. 20%

  4. 24%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When length and breadth both increase by 10%, new area = (1.10L) × (1.10B) = 1.21LB. The increase is 21%. Alternatively: successive percentage changes of 10% and 10% follow the formula a + b + (ab/100) = 10 + 10 + (10×10/100) = 21%. Option B (21%) is correct. Options A (22%), C (20%), and D (24%) are incorrect.

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