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0580/21 May/Jun 2025, Question 12: Finding the Median and Quartiles

Cambridge IGCSE Mathematics 0580 · Paper 21 (Extended) · Non-calculator · 4 marks

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The question, in short

From a cumulative frequency curve for 120 adults' daily internet time, estimate the interquartile range and the time below which 70% of adults fall.

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

Part (a) · 2 marks

Use the cumulative frequency diagram to estimate the interquartile range of the times.

  1. 1LQ at cumulative frequency 1/4 × 120 = 30: LQ = 4.2
  2. 2UQ at cumulative frequency 3/4 × 120 = 90: UQ = 5.6
  3. 3IQR = 5.6 − 4.2 = 1.4

Answer1.4

Part (b) · 2 marks

Use the cumulative frequency diagram to estimate k, where 70% of adults spent less than k hours.

  1. 170% of 120 = 0.7 × 120 = 84
  2. 2Read across from 84 to the curve and down: k = 5.4

Answer5.4

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