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Cumulative frequency adds up frequencies to plot a cumulative frequency graph, used to estimate the median, quartiles and interquartile range of grouped data. It's examined right across GCSE and iGCSE Maths. Learn it free on eClassroom through guided worked examples and instantly-marked exam-style questions.
How you do it
Add the frequencies as you go and plot each running total at the upper boundary of its class, then join with a smooth curve. Read the median at half the total, the lower quartile at a quarter and the upper at three quarters. The interquartile range is the difference between the quartiles.
Before you start
Check grouped frequency and averages first if this feels hard. It leads on to box plots, quartiles and the interquartile range. This is a Higher tier topic.
What you learn
A cumulative frequency curve lets us estimate the median and quartiles of grouped data. We build a running total, plot a curve, and read values straight off it. Cumulative frequency is a running total — the number of values up to and including the top of each class. The course works through cumulative frequency tables, plotting the curve and quartiles and the IQR. Every section has instant-feedback practice questions matched to Edexcel iGCSE 4MA1 and the other major GCSE boards, and the course finishes with full exam-style questions you mark yourself.
Related Topics
We teach Cumulative Frequency as one of the Data and Statistics topics in our GCSE course library, at Higher tier. There are 3 teaching sections and 2 fully worked examples, plus 3 sets of check questions. Students often pair it with Histograms, Types of Data and Averages — Frequency Tables. For unlimited practice, the Data and Statistics revision engine builds new questions on demand and records your accuracy.
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