EDEXCEL GCSE FOUNDATION MATHS - What are Pie Charts

Edexcel GCSE Foundation Maths: Pie Charts

What is a Pie Chart?

A pie chart is a circular graph that shows the proportion of a whole that each category represents. It’s like dividing a pie into slices, where each slice represents a different part of the whole.

Key Features of a Pie Chart:

• Circle: The whole pie represents the entire data set.
• Slices: Each slice represents a different category.
• Size of the slice: The size of the slice is proportional to the amount of data it represents.
• Labels: Each slice is labelled with the category it represents.
• Percentage or angle: The percentage or angle of each slice can be shown to represent the proportion of the whole.

Example:

Imagine a pie chart showing the favourite colours of 20 students:

• Red: 8 students
• Blue: 6 students
• Green: 4 students
• Yellow: 2 students

Steps to Create a Pie Chart:

1. Calculate the proportion: For each category, divide the number of students by the total number of students (20). * Red: 8/20 = 0.4 * Blue: 6/20 = 0.3 * Green: 4/20 = 0.2 * Yellow: 2/20 = 0.1
2. Convert to percentages: Multiply each proportion by 100. * Red: 0.4 x 100 = 40% * Blue: 0.3 x 100 = 30% * Green: 0.2 x 100 = 20% * Yellow: 0.1 x 100 = 10%
3. Calculate the angle: To find the angle of each slice, multiply the percentage by 360 degrees (a full circle). * Red: 40% x 360° = 144° * Blue: 30% x 360° = 108° * Green: 20% x 360° = 72° * Yellow: 10% x 360° = 36°
4. Draw the pie chart: Using a compass, draw a circle. Using a protractor, draw the angles of each slice. Label each slice with the category and the percentage.

Advantages of Pie Charts:

• Easy to understand and interpret.
• Visually appealing.
• Show the proportions of a whole.

Disadvantages of Pie Charts:

• Difficult to compare different pie charts.
• Not suitable for large datasets.
• Cannot show precise values.

Applications of Pie Charts:

Pie charts are used in various fields:

• Business: Show market share, sales figures, and customer demographics.
• Education: Represent student performance, subject choices, and attendance.
• Health: Show disease prevalence, population demographics, and health trends.
• Finance: Represent income sources, expenses, and portfolio allocation.

Practice Problems:

1. Create a pie chart showing the favourite sports of 30 students: * Football: 15 * Basketball: 8 * Tennis: 5 * Swimming: 2

2. A survey of 100 people was conducted to find their favourite type of music: * Pop: 40 * Rock: 30 * Classical: 20 * Jazz: 10 * Create a pie chart to represent this data.

Remember:

• The total percentage of all slices in a pie chart should always add up to 100%.
• The angles of all slices in a pie chart should always add up to 360°.

By understanding the concept of pie charts, you can effectively interpret data and communicate information visually in various contexts.