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A frequency is a count, and a frequency tree shows how one total is split into categories such as boys and girls or tea and coffee. The first node is usually the grand total, and each new split breaks a group into smaller parts.
At every split, the two child numbers add back to the parent number. If one child is missing, use the following calculation to find the value:
missing child=parent total−known child \text{missing child} = \text{parent total} - \text{known child} missing child=parent total−known childFor example, if 909090 students are split into set A and set B, and 343434 are in set A, then set B has 90−34=5690 - 34 = 5690−34=56. This same add-then-subtract idea is the backbone of every frequency tree question.
Question 1
4 marks30 people took a literacy test and a numeracy test.
23 of the people passed the literacy test.
In a frequency tree, what is a frequency?
Revision notes for Edexcel GCSE Maths Frequency Trees. Open the guide for explanations and worked examples. Written against the Edexcel GCSE Maths (1MA1) specification, so the content matches what's examinable rather than general Maths background.
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A frequency tree starts with 62 students and first splits into boys and girls. There are 27 boys. How many girls are there?
