The length of a rectangular increased by 10% and it;s breadth is decreased by 10 %. Then the area of the 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. After the changes, the new area is 110% of L × 90% of B, so it is 1.10 × 0.90 = 0.99 times the original area. The area is therefore 99% of its original value, a decrease of 1%. Students often choose a because they incorrectly cancel the 10% increase and decrease instead of multiplying the percentage factors.
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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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