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When data is grouped into class intervals, this topic estimates the mean using midpoints and identifies the modal class and the class containing the median from a grouped frequency table. It's examined right across GCSE and iGCSE Maths. Work through it free on eClassroom, with clear worked examples and instantly-marked questions that build your confidence for the exam.
How you do it
Use the midpoint of each class as the value, multiply by the frequency, add up and divide by the total. The answer is an estimate because the original values are lost. The modal class is the group with the highest frequency, not the highest number.
Before you start
Get averages from frequency tables straight before you begin. Later work on cumulative frequency and histograms assumes it.
What you learn
When data is sorted into class intervals we no longer know each exact value, so we estimate the mean using midpoints, and describe the average with the modal class and the class containing the median. In a grouped table each row is a range of values. We can’t give an exact median from grouped data, but we can say which class it lies in. The course works through grouped data and midpoints, estimating the mean and the class containing the median. 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
Averages — Grouped Frequency is a Data and Statistics topic in the GCSE syllabus, covered here at Foundation tier. It runs to 3 concepts, each followed by a check, with 2 worked examples along the way. It sits alongside Averages — Raw Data, Charts & Diagrams, Comparing Distributions, Cumulative Frequency and Histograms in the same strand. For unlimited practice, the Data and Statistics revision engine builds new questions on demand and records your accuracy.
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