The length of a rectangle is increased by $20\%$ and the breadth is decreased by $20\%$. The percentage…

The length of a rectangle is increased by $20\%$ and the breadth is decreased by $20\%$. The percentage change in area is:
  1. Increase of $4\%$
  2. Decrease of $4\%$
  3. No change
  4. Decrease of $20\%$

Solution

New area $= (1.2 l)(0.8 b) = 0.96 \, lb$. So area decreases by $4\%$.

Asked in: IMO

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