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4024/11 May/Jun 2020, Question 13: Percentage Increases and Decreases

Cambridge O Level Mathematics 4024 · Paper 11 (Non-calculator) · Non-calculator · 3 marks

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The question, in short

Two percentage-change problems: a village population rising from 200 to 250, and a rectangle whose length rises 10% while its width falls 10%.

Summarised in our own words. Use the official paper for the exact wording and any diagrams.

Part (a) · 1 mark

Work out the percentage increase when the population goes from 200 to 250.

  1. 1Increase = 250 − 200 = 50
  2. 2Percentage increase = 50/200 × 100 = 25%

Answer25

Part (b) · 2 marks

Express the new rectangle's area as a percentage of the original area after a 10% length increase and 10% width decrease.

  1. 1New length = 1.1 × length, new width = 0.9 × width
  2. 2New area = 1.1 × 0.9 × original area = 0.99 × original area
  3. 3New area = 99% of the original area

Answer99

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