Knowledge Organiser: Box Plots
Part of Box Plots · GCSE GCSE Mathematics revision
This topic summary covers Knowledge Organiser: Box Plots within Box Plots for GCSE Mathematics. Revise Box Plots in Statistics for GCSE Mathematics with 18 exam-style questions and 20 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 11 of 11 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 11 of 11
Practice
18 questions
Recall
20 flashcards
Knowledge Organiser: Box Plots
Key Terms
- Box plot: A diagram showing the five-number summary of a dataset
- Five-number summary: Minimum, Q1, Median (Q2), Q3, Maximum
- Box: Spans Q1 to Q3, representing the middle 50% of data
- Whiskers: Lines from the box to the minimum and maximum values
- IQR: Q3 − Q1 — the width of the box
- Outlier: A value more than 1.5 × IQR beyond Q1 or Q3; plotted separately
Must-Know Facts
- Always sort data into ascending order before finding quartiles
- Q1 < Median < Q3 — always check this holds
- The median line must sit inside the box, never outside it
- Compare medians to compare typical values between two datasets
- Compare IQRs to compare consistency — smaller IQR = more consistent
- Skewness: median closer to Q1 = positive skew; closer to Q3 = negative skew
- Use a ruler and a consistent scale when drawing box plots
Key Formulas
- IQR = Q3 − Q1
- Range = Maximum − Minimum
- Lower outlier fence = Q1 − 1.5 × IQR
- Upper outlier fence = Q3 + 1.5 × IQR
Common Mistakes
- Confusing range with IQR: Box plot shows IQR (the box width) AND range (total whisker span) — they are different
- Whiskers to outliers: Whiskers extend to the furthest value within the fences, NOT always to the min/max
- Median position: The line inside the box is the median — it may not be in the centre (skewed data)
- Comparing two box plots: Comment on median (average), IQR (spread/consistency), and any overlap
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Read this section alongside the surrounding pages in Box Plots. That gives you the full topic sequence instead of a single isolated revision point.
Practice Questions for Box Plots
On a box plot, what does the box (the rectangle) represent?
Two athletics clubs record the 100m sprint times (in seconds) for their members. The five-number summaries are shown below. Club A: Min = 11.2, Q1 = 12.4, Median = 13.1, Q3 = 14.2, Max = 16.5 Club B: Min = 12.0, Q1 = 13.5, Median = 14.8, Q3 = 16.1, Max = 17.3 Compare the distributions of sprint times for the two clubs. You must use the data to support your answer. (3 marks)
Quick Recall Flashcards
18 questions on Box Plots — practise free
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