IGCSE Maths / Working with data

Quartiles and the interquartile range for discrete data revision notes

Edexcel International GCSE Maths (4MA1), chapter 19: Working with data, specification point 6.2c. Part of the full course.

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Quartiles divide sorted data into four equal-sized parts. For discrete data, find the quartile positions using n + 1, read off the values, then calculate the interquartile range (IQR) as Q₃ − Q₁.

More lessons in Working with data

• Bar charts, pie charts and pictograms
• Two-way tables and reading statistical diagrams
• Mean from a frequency table
• Estimated mean and modal class for grouped data
• Frequency density
• Drawing a histogram
• Reading frequencies from a histogram
• Completing a histogram from a part drawn graph
• Estimating a frequency within a class
• Building a cumulative frequency table
• Plotting a cumulative frequency diagram
• Reading values from a cumulative frequency graph
• Estimating how many are above or below a value
• Estimating the median from a cumulative frequency diagram
• Estimating the interquartile range from a cumulative frequency diagram
• Comparing two cumulative frequency distributions
• Mean, median, mode and range
• What a measure of spread tells you
• Using the interquartile range to compare distributions