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Which average is best to use for the data set [2, 3, 3, 4, 4, 4, 5, 100]?
The mean The median (4)
Statistics & Probability is a core part of GCSE Maths. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts Mean Add all values, divide by how many there are
Median Middle value once data is sorted in order
Mode Value that appears most often in the data
Range Largest value minus smallest value
Discrete data Counts only certain values, like number of pets
Continuous data Can take any value, like height or time
IQR Upper quartile minus lower quartile — middle 50% spread
Box plot Diagram showing min, Q1, median, Q3, max
Correlation How two variables change together on a scatter graph
Line of best fit Straight line drawn through the trend of points
Interpolation Reading within the range of the data — reliable
Extrapolation Reading outside the data range — unreliable
Frequency How many times a value or class appears
Modal class Grouped class with the highest frequency
Show all 14 key concepts What your exam board covers Where Statistics & Probability sits in each exam board's specification. Tap a board to see what it lists.
AQA Probability Spec 8300 Probability and outcomes Combined events, tree diagrams and Venn diagrams Source: AQA GCSE Mathematics (8300) specification — Subject content , accessed 23 June 2026.
AQA Statistics Spec 8300 Sampling Data presentation and interpretation Measures of central tendency and spread Source: AQA GCSE Mathematics (8300) specification — Subject content , accessed 23 June 2026.
Edexcel Probability Spec 1MA1 Probability and combined events Source: Pearson Edexcel GCSE (9–1) Mathematics (1MA1) specification , accessed 23 June 2026.
Edexcel Statistics Spec 1MA1 Sampling, presentation and interpretation of data Source: Pearson Edexcel GCSE (9–1) Mathematics (1MA1) specification , accessed 23 June 2026.
Eduqas/WJEC Probability Spec C300QS Source: Eduqas GCSE Mathematics specification , accessed 9 July 2026.
Eduqas/WJEC Statistics Spec C300QS Source: Eduqas GCSE Mathematics specification , accessed 9 July 2026.
OCR Probability Spec J560 Basic probability and experiments Combined events and probability diagrams Source: OCR GCSE (9–1) Mathematics (J560) specification , accessed 23 June 2026.
OCR Statistics Spec J560 Sampling Interpreting and representing data Analysing data Source: OCR GCSE (9–1) Mathematics (J560) specification , accessed 23 June 2026.
Cambridge IGCSE Probability Spec 0580 Introduction to probability Relative and expected frequencies Probability of combined events Conditional probability Source: Cambridge IGCSE Mathematics (0580) syllabus , accessed 23 June 2026.
Cambridge IGCSE Statistics Spec 0580 Classifying statistical data Interpreting statistical data Averages and measures of spread Statistical charts and diagrams Scatter diagrams Cumulative frequency diagrams Histograms Source: Cambridge IGCSE Mathematics (0580) syllabus , accessed 23 June 2026.
Edexcel IGCSE Statistics and probability Spec 4MA1 Graphical representation of data Statistical measures Probability Source: Pearson Edexcel International GCSE Mathematics (Spec A) (4MA1) specification , accessed 23 June 2026.
L Learn Statistics & Probability step by step
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Common mistakes to avoid Questions where students often pick the tempting wrong answer — make sure you know the right one:
Which average is best to use for the data set [2, 3, 3, 4, 4, 4, 5, 100]? ✗ The mean — it always gives the most accurate average. ✓ The median (4) — it isn't distorted by the outlier 100, unlike the mean.
What is the range of the data set [4, 7, 2, 9, 5]? ✗ From 2 to 9 — the range is given as two values. ✓ 7 — the largest minus the smallest (9 - 2).
If a data set has an extreme outlier, which average is most affected? ✗ The median is most affected because the outlier shifts the middle. ✓ The mean — because every value (including the outlier) contributes to it.
Which of these is CONTINUOUS data? ✗ Number of pets owned ✓ Height of a tree
On a box plot, what does the IQR measure? ✗ Total range of data ✓ Spread of the middle 50%
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