The length of a rectangle is increased by 10 % and breadth decreased by 10 % Then the area of a new rectangle is:_________?
Correct answer: C. decreased by 1 %
- A. neither increased nor decreased
- B. increased by 1 %
- C. decreased by 1 %
- D. decreased by 10 %
Explanation
Let the original area be L × B. The new area is 1.10L × 0.90B = 0.99LB, so it is 1% less than the original area. Students often choose a because they assume a 10% increase and a 10% decrease cancel exactly.
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About Percentages
Percentages express a quantity as parts per hundred and support calculations involving increases, decreases, discounts, commissions, taxes, and successive changes. Questions require distinguishing percentage change from percentage points and identifying the original value when a final value and its percentage change are given.
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