4MA1/1HR Jan 2021, Question 18: Histograms (Unequal Class Intervals)
Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 1HR (Higher) · Calculator · 5 marks
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The question, in short
Use the histogram bar heights and the given frequency for 0 < t ≤ 2 to complete the table, then estimate the mean homework time in hours to 3 significant figures.
Summarised in our own words. Use the official paper for the exact wording and the diagram.
Solution · 5 marks
- 1First bar: frequency density = 28 ÷ 2 = 14, so one large square = 4
- 2Frequencies: 2 × 20 = 40, 1 × 30 = 30, 1 × 24 = 24, 3 × 12 = 36
- 3Midpoint × frequency: 1×28 + 3×40 + 4.5×30 + 5.5×24 + 7.5×36 = 685
- 4Total frequency = 28 + 40 + 30 + 24 + 36 = 158
- 5Mean = 685 ÷ 158 = 4.335… = 4.34
Answer4.34
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