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4MA1/1H Jun 2020, Question 18: Histograms (Unequal Class Intervals)

Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 1H (Higher) · Calculator · 5 marks

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The question, in short

Using a grouped frequency table of plant heights in cm, draw a histogram and estimate how many plants are taller than 40 cm.

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

Part (a) · 3 marks

Draw a histogram on the given grid from the grouped heights and frequencies, using unequal class widths.

  1. 1Frequency density = frequency ÷ class width
  2. 235 ÷ 10 = 3.5, 45 ÷ 15 = 3, 75 ÷ 15 = 5
  3. 340 ÷ 20 = 2, 8 ÷ 10 = 0.8
  4. 4Draw bars at these heights and label the vertical axis frequency density with a scale

AnswerA fully correct histogram with frequency density and scale on the axis labelled

Part (b) · 2 marks

Estimate the number of plants with height greater than 40 cm from the table.

  1. 135 < h ≤ 50 is 15 cm wide with 75 plants: 75 ÷ 15 = 5 per cm.
  2. 2From 40 to 50 is 10 cm: 10 × 5 = 50 plants
  3. 3Plants above 50 cm: 40 + 8 = 48
  4. 4Total = 50 + 48 = 98

Answer98

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