Year 11 - Maths
Interquartile range
Graphical representations of data: cumulative frequency and histograms
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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 consider cumulative frequency graphs and histograms, and compare these with other known graphical representations.
Lesson Summary
You will learn to calculate the IQR and interpret what this means.
Key Notes
- The interquartile range tells us how spread out the middle 50% of the data is
- This can be seen visually with a box plot
- Box plots and cumulative frequency graphs can be compared
- This comparison involves the median and interquartile range
Vocabulary To Learn
- Interquartile range: Interquartile range is calculated by finding Q3 − Q1. This is because it is the range from the first to the third quartile.
Common Mistakes To Avoid
- Not referring to the context of the question when comparing the data.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
The interquartile range tells us how spread out the middle 50% of the data is. This can be seen visually with a box plot.
2. Use this key word in a maths sentence and explain it clearly. 'Interquartile range'
Interquartile range is calculated by finding Q3 − Q1. This is because it is the range from the first to the third quartile. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Not referring to the context of the question when comparing the data. Correction: Highlight that just saying the median or the interquartile is bigger is of little use unless you know what the data was about.
More Lessons In This Unit
- Comparing box plots Study Guide
- Constructing a cumulative frequency graph Study Guide
- Constructing box plots Study Guide
- Constructing histograms and box plots using technology Study Guide
- Histograms with equal bar width Study Guide
- Histograms with unequal bar width Study Guide
- Interpreting a cumulative frequency graph Study Guide
- Moving between tables and histograms Study Guide
- Problem solving with cumulative frequency and histograms Study Guide
- Summary statistics from histograms Study Guide
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