Draw and read bar charts and dual bar charts, then compare categories using the scale. It is a Foundation topic, aimed at grade 2. Free questions with answers are on this page. Worked examples show each line before you try the questions.
Bar charts show frequencies of categories. The height is the frequency; the bars are equal width with gaps. Dual (or compound) bars put two groups side by side for each category so you can compare boys against girls, or this year against last year, without losing the totals.
Read the scale — it may go up in 2s or 5s, and a bar that stops between lines needs care. Total frequency is the sum of every bar. For a dual chart, add the pair of bars in that category to get the category total.
Do not turn a bar chart into a histogram in your head. These bars are categories, not grouped number classes, so there is no frequency density and no joining of bars.
Objectives
The side scale may go up in 1s, 2s or 5s.
The taller bar has the higher frequency.
Bars for categories have gaps, because the categories are separate.
Key points
Read a value from a bar chart using the scale on the frequency axis.
Draw a bar chart with equal-width bars, gaps between them, labelled axes and a title.
Compare two groups on a dual bar chart.
Find a missing frequency using the total.
Worked examples
Example 1
In a bar chart the bar for walk has height 3 and the bar for bus has height 7. How many more people took the bus than walked?
1 marks
The bus bar is 7 and the walk bar is 3. How many more means subtract.
7 − 3 = 4.
4 more people took the bus.
Answer: 4
Common slips
Slip: The bus bar is 9 and the walk bar is 3. How many more means subtract. That changes a number from the question, so it answers a different question.
Slip: 7 + 3 = 10. That uses addition, but this step needs subtraction.
Slip: 8 more people took the bus. That does not match the working above it.
Example 2
A bar chart shows how pupils travel to school. The bars for walk, bus and car have heights 4, 8 and 5. How many pupils are shown altogether?
2 marks
The total is the sum of every bar height: 4 + 8 + 5.
4 + 8 = 12, then 12 + 5 = 17.
17 pupils are shown altogether.
Answer: 17
Common slips
Slip: The total is the sum of every bar height: 6 + 8 + 5. That changes a number from the question, so it answers a different question.
Slip: 7 + 8 = 12, then 12 + 5 = 17. That changes a number in the working, so the step no longer follows from the one before.
Slip: 21 pupils are shown altogether. That does not match the working above it.
Example 3
A bar chart of 20 pupils has three bars. Two of the bars have heights 7 and 6. What is the height of the third bar?
2 marks
The three bars must add up to 20. The two known bars add to 7 + 6 = 13.
20 − 13 = 7.
The third bar has height 7.
Answer: 7
Common slips
Slip: The three bars must add up to 22. The two known bars add to 7 + 6 = 13. That changes a number from the question, so it answers a different question.
Slip: 20 + 13 = 33. That uses addition, but this step needs subtraction.
Slip: The third bar has height 11. That does not match the working above it.
Questions and answers
GCSE Maths bar charts questions and answers. Try each one, then open the answer. Easy questions come first.
Question 1 Easy2 marks
A dual bar chart shows pupils in a club. The boys' bar has height 12 and the girls' bar has height 7. How many more boys than girls are there?
Show answer
Answer: 5
Both bars are for the same club, so they can be compared. Boys 12, girls 7.
12 − 7 = 5.
M1 — Both bars are for the same club, so they can be compared. Boys 12, girls 7.
A1 — Answer 5
Question 2 Easy2 marks
In a bar chart the bar for walk has height 7 and the bar for bus has height 12. How many more people took the bus than walked?
Show answer
Answer: 5
The bus bar is 12 and the walk bar is 7. How many more means subtract.
12 − 7 = 5.
M1 — The bus bar is 12 and the walk bar is 7. How many more means subtract.
A1 — Answer 5
Question 3 Medium2 marks
A dual bar chart shows pupils in a club. The boys' bar has height 16 and the girls' bar has height 12. How many more boys than girls are there?
Show answer
Answer: 4
Both bars are for the same club, so they can be compared. Boys 16, girls 12.
16 − 12 = 4.
M1 — Both bars are for the same club, so they can be compared. Boys 16, girls 12.
A1 — Answer 4
Question 4 Medium2 marks
In a bar chart the bar for walk has height 11 and the bar for bus has height 17. How many more people took the bus than walked?
Show answer
Answer: 6
The bus bar is 17 and the walk bar is 11. How many more means subtract.
17 − 11 = 6.
M1 — The bus bar is 17 and the walk bar is 11. How many more means subtract.
A1 — Answer 6
Question 5 Hard2 marks
A dual bar chart shows pupils in a club. The boys' bar has height 20 and the girls' bar has height 17. How many more boys than girls are there?
Show answer
Answer: 3
Both bars are for the same club, so they can be compared. Boys 20, girls 17.
20 − 17 = 3.
M1 — Both bars are for the same club, so they can be compared. Boys 20, girls 17.
A1 — Answer 3
Question 6 Hard2 marks
In a bar chart the bar for walk has height 15 and the bar for bus has height 19. How many more people took the bus than walked?
Show answer
Answer: 4
The bus bar is 19 and the walk bar is 15. How many more means subtract.
19 − 15 = 4.
M1 — The bus bar is 19 and the walk bar is 15. How many more means subtract.
A1 — Answer 4
Question 7 Exam-style2 marks
A dual bar chart shows pupils in a club. The boys' bar has height 24 and the girls' bar has height 22. How many more boys than girls are there?
Show answer
Answer: 2
Both bars are for the same club, so they can be compared. Boys 24, girls 22.
24 − 22 = 2.
There are 2 more boys than girls.
M1 — Both bars are for the same club, so they can be compared. Boys 24, girls 22.
A1 — Answer 2
Common mistakes
Most lost marks on this topic are one slip.
Reading the category label as the frequency.
The frequency is the height.
Forgetting the scale goes up in twos.
Count the grid spacing before you read a bar.
Leaving a gap out of a total.
Every bar is part of the total.
Spot the slip
A bar of height 7 means the frequency is
7
14
the label under the bar
Show the slip
7 Read the height against the scale.
Exam tips
This topic can appear on a calculator or a non-calculator paper. Show enough working for a method mark.
If the question says “show that”, the result is given. The marks are for the steps that reach it.
The method is the same on AQA-style and Edexcel-style papers.
When a total is given, add the bars you know and subtract — write both lines so the method is visible.
Use a ruler for bars and check each bar height against the scale before moving on.
Printable worksheet
The same questions are in a PDF you can print. Answers start on a later page.