A-level · Data presentation

Histograms and frequency polygonsExam-style questions

Why a histogram for continuous data plots frequency DENSITY, not frequency, so that the AREA of each bar is proportional to the frequency — and how that one rule lets you find a missing frequency, a missing class width, or read a frequency off a drawn bar. Plus the frequency polygon, which joins class midpoints.

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16 questions · A-level level · mark scheme and worked solution on each · no sign-up to try

DifficultyAll Level 2 Level 3 Level 4 Level 5

1
The histogram summarises the volumes of water, in litres, used on one particular day by each of the 160 households in a village.On that day, 35 of the households used between 100 and 150 litres of water.
(a) Find the number of households that used between 300 and 500 litres of water on that day.

(1 mark)
(b) State the units of the frequency density.

(1 mark)
(c) The water company wants to use the histogram to learn more about the households that used the most water. Suggest one change to the histogram that would help with this.

(1 mark)
(d) Estimate the number of households that used between 400 and 500 litres of water on that day.

(1 mark)
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