IGCSE Math RevisionReading charts and tables: GCSE Maths grade 4 basics
Read the chart carefully, then do a small calculation. Most marks here are lost by misreading a scale or mixing up the value with the frequency.
In plain English
- Bar charts: check the scale on the vertical axis first. Each square might be worth 1, 2 or 5.
- Pie charts: the whole circle, 360°, is everyone. Number of people = angle ÷ 360 × total.
- Averages: mean = total ÷ how many; median = the middle value in order; mode = the most common; range = biggest − smallest.
- Frequency tables: the frequency says how many times each value happened. For the total, multiply each value by its frequency and add.
Worked example
20 people were asked how many pets they have. 5 have 0 pets, 8 have 1, 4 have 2 and 3 have 3. Find the mean number of pets.
- Total pets: 0 × 5 + 1 × 8 + 2 × 4 + 3 × 3 = 0 + 8 + 8 + 9 = 25
- Number of people: 5 + 8 + 4 + 3 = 20
- Mean = 25 ÷ 20 = 1.25 pets
Answer: 1.25
Most common mistake
Each row stands for many people or results. Divide by how many people there are (the total frequency), not by how many rows the table has.
Practice questions (11)
Try each one on paper first, then open the worked answer and mark yourself. You don't need a calculator for any of these.
Books borrowed from a library, Monday to Friday Books borrowed from a library, Monday to Friday Mon 12 Tue 8 Wed 15 Thu 10 Fri 5 Each small gridline is 1 book.
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Q1.Use the bar chart. How many books were borrowed on Wednesday?
Show worked answer
- Read the top of Wednesday's bar against the scale
- It reaches 15
Answer: 15
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Q2.How many books were borrowed altogether from Monday to Friday?
Show worked answer
- 12 + 8 + 15 + 10 + 5
- = 50
Answer: 50
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Q3.What is the difference between the most and the fewest books borrowed on one day?
Show worked answer
- Most: 15 (Wednesday). Fewest: 5 (Friday)
- 15 − 5 = 10
Answer: 10
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Q4.Work out the mean number of books borrowed per day.
Show worked answer
- Total = 50 books
- Number of days = 5
- Mean = 50 ÷ 5 = 10
Answer: 10
Favourite sport of 60 students - Football: 150°
- Tennis: 60°
- Swimming: 90°
- Other: 60°
Favourite sport of 60 students Football 150° Tennis 60° Swimming 90° Other 60° -
Q5.Use the pie chart. The Football sector has an angle of 150°. How many of the 60 students chose football?
Show worked answer
- Football is 150/360 of the circle
- 150/360 × 60 = 25
Answer: 25
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Q6.How many students chose swimming (90°)?
Show worked answer
- 360° stands for 60 students, so each student is 360 ÷ 60 = 6°
- 90 ÷ 6 = 15 students
Answer: 15
Goals scored by a team in 20 matches Goals 0 1 2 3 Frequency 4 7 6 3 -
Q7.Use the table. What is the modal number of goals?
Show worked answer
- The mode is the value with the highest frequency
- The highest frequency is 7, for 1 goal
Answer: 1 goal
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Q8.How many goals were scored altogether in the 20 matches?
Show worked answer
- Multiply each number of goals by its frequency
- 0 × 4 + 1 × 7 + 2 × 6 + 3 × 3 = 0 + 7 + 12 + 9
- = 28 goals
Answer: 28
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Q9.Work out the mean number of goals per match.
Show worked answer
- Total goals = 28
- Number of matches = 4 + 7 + 6 + 3 = 20
- Mean = 28 ÷ 20 = 1.4
Answer: 1.4
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Q10.Find the median number of goals.
Show worked answer
- There are 20 matches, so the median is halfway between the 10th and 11th values
- 0 goals: matches 1 to 4. 1 goal: matches 5 to 11
- The 10th and 11th values are both 1
Answer: 1 goal
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Q11.Find the range of these numbers: 7, 3, 12, 9, 4
Show worked answer
- Biggest = 12, smallest = 3
- Range = 12 − 3 = 9
Answer: 9
Can you do these?
- Read values from bar charts and tables, using the scale
- Read and draw pie charts using 360°
- Find the mean, median, mode and range of a list
- Find the mean and mode from a frequency table
Tick them off on the printable checklist. Want more? The Core sections of our free statistics notes cover the same maths (they are written for IGCSE, but the basics are the same).