Bar and Composite Bar Charts
A bar chart is a diagram that uses rectangular bars of equal width, with heights proportional to frequency, to display and compare categorical data, while a composite (or stacked) bar chart splits each bar into sub-categories stacked on top of each other so totals and breakdowns can both be read from one chart. Both are drawn and interpreted in the Processing and Representing Data strand of GCSE Statistics.
Before you start
Make sure you're comfortable with these topics first:
Method
- Draw and label two axes: the categories on one axis with equal-width bars and equal gaps, and frequency on the other axis with a scale starting at 0.
- For a simple bar chart, draw one bar per category with height equal to its frequency.
- For a composite bar chart, split each category's bar into sections, stacking each sub-group's frequency on top of the last so the full bar height equals the category total.
- Add a key showing which shading or colour represents each sub-group.
- To read a section of a composite bar, subtract the value where it starts from the value where it ends.
- Compare categories by comparing bar heights, or compare sections by comparing their lengths.
Worked example
A composite bar chart shows the number of students at School A and School B choosing football or netball, with football stacked below netball in each bar. School A: football 18, total bar height 30. School B: football section drawn from 0 up to 14, with the whole bar reaching 26. Find how many students at School B chose netball, and state which school had more students choosing football.
- School B football = 14 (the height of the bottom section).
- School B total = 26, so School B netball = 26 - 14 = 12.
- School A football = 18, School B football = 14.
- 18 is greater than 14.
- Final answer: School B netball = 12 students; School A had more football players (18 compared with 14).
Practice questions
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Q1A bar chart shows 3 bars: Dogs 12, Cats 9, Rabbits 5. How many pets are shown in total?Show answer
Answer: 26 (12 + 9 + 5)
Q2A bar chart shows the bar for 'Bus' with height 40 and the bar for 'Walk' with height 25. How many more pupils travel by bus than walk?Show answer
Answer: 15 (40 - 25)
Q3A composite bar for Year 7 shows Boys 20 stacked below Girls, with a total bar height of 45. How many girls are there?Show answer
Answer: 25 (45 - 20)
Q4A bar chart uses a scale where each small square represents 2 people. A bar is 7 squares tall. How many people does the bar represent?Show answer
Answer: 14 people (7 x 2)
Q5Two composite bars compare tea and coffee drinkers: Monday has a total of 60 drinks, of which 35 are tea; Tuesday has a total of 72 drinks, of which 40 are tea. On which day was a greater proportion of drinks tea?Show answer
Answer: Monday (35/60 = 58.3% compared with 40/72 = 55.6%)
Q6A composite bar chart shows exam grades at a school: the bar has a section from 0 to 10 for Grade 9-7, a section from 10 to 34 for Grade 6-4, and a section from 34 to 40 for Grade 3-1. How many students got Grade 6-4?Show answer
Answer: 24 students (34 - 10)
Exam-style questions
Written in the style of a GCSE Statistics exam paper, with a full mark scheme.
A bar chart shows the number of pupils who chose four different lunch options. Sandwiches 24, Pasta 18, Salad x, Jacket potato 15. The total number of pupils is 75. Work out x, the number of pupils who chose salad.
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A composite bar chart compares hours of sunshine and rain in a week for two towns. Town P has 30 hours of sunshine and a total bar height of 42 hours. Town Q has 22 hours of sunshine and 15 hours of rain. (a) Work out the number of hours of rain in Town P. (b) State which town had more total hours of sunshine and rain combined.
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The table shows gym members in two age groups. Under 30: male 45, female 55. 30 and over: male x, female 70, with the total number of members aged 30 and over equal to 150. (a) Find x. (b) A composite bar chart shows one bar per age group, split into a male section from 0 to x and a female section above it. State the length of the female section of the '30 and over' bar.
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See real GCSE Statistics past-paper questions, with official mark schemes →
Free printable worksheet
Want more practice on paper? Download the bar and composite bar charts worksheet pack - 17 pages of exam-style questions with a full mark scheme. One email opens every download in this browser for 14 days - no account, no card. Print it for personal and classroom use.
This topic is chapter 16 of GCSE Statistics Foundation Workbook 1 and chapter 20 of GCSE Statistics Higher Workbook 1, the whole course as one free printable PDF.
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