Year 8 - Maths
Calculating the mean
Numerical summaries of data
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils explore the concept of measures of central tendancy, developing understanding of different types of average and their relative benefits and drawbacks. We then investigate other summaries of data such as the range and data comparison techniques.
Lesson Summary
You will learn to calculate the mean from data presented in a frequency table and different graphs.
Key Notes
- The mean can be calculated from a line graph.
- The mean can be calculated from an ungrouped frequency table.
- The mean can be calculated from a bar chart.
Vocabulary To Learn
- Frequency: The frequency is the number of times an event occurs; or the number of individuals (people, animals etc.) with some specific property.
- Data: Data are a collection of information.
- Mean: The sum of the values divided by the number of values. It is a measure of central tendency representing the average of the values.
- Measure of central tendency: A summary measure that attempts to describe a whole set of data with a single value that represents the middle of the distribution.
Common Mistakes To Avoid
- Pupils may divide by how many groups/bars there are, instead of the total frequency.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
The mean can be calculated from a line graph. The mean can be calculated from an ungrouped frequency table.
2. Use this key word in a maths sentence and explain it clearly. 'Frequency'
The frequency is the number of times an event occurs; or the number of individuals (people, animals etc.) with some specific property. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Pupils may divide by how many groups/bars there are, instead of the total frequency. Correction: By reminding students frequently that averages need to give a 'typical' value of the data set, ask them to sense check their mean value.
More Lessons In This Unit
- Analysing different statistical representations Study Guide
- Calculating the median Study Guide
- Calculating the mode Study Guide
- Changing a data point Study Guide
- Checking understanding of the mean Study Guide
- Comparing statistical representations Study Guide
- Comparing summaries of data Study Guide
- Correlation Study Guide
- Evaluating the range Study Guide
- Problem solving with numerical summaries of data Study Guide
- Statistical problems - data collection Study Guide
- Statistical problems - data presentations Study Guide
- Statistical problems - drawing conclusions Study Guide
- Statistical problems - statistical summaries Study Guide
- Summarising data Study Guide
- Understanding and calculating the range Study Guide
- Understanding the median Study Guide
- Understanding the mode Study Guide
Browse all guides in the Year 8 Maths guide library.