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5
2+3.
O Level · English Medium · Pearson Edexcel · Mathematics
Data, probability and written reasoning
Interpret grouped data and probability trees with limits stated.
About this lesson and its coverage
Original Kidemy O Level progression. This level has its own text, examples and questions. Curriculum versions share the progression; complete board-specific coverage still needs specification matching and additional material.
Learn the idea
A grouped mean estimated from interval midpoints loses within-interval information. Probability trees separate ordered events. Independent draws with replacement use the same composition; without replacement they usually do not.
Worked example
Values in intervals[0,10),[10,20) with frequencies2,3 give midpoint estimate(5×2+15×3)/5=11. The exact individual mean may differ.
- Identify the quantities and restrictions.
- Show a method with units or symbols.
- Check and explain the result.
Your written practice
Show your working on paper. Check your answer, then choose Next.
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11
55/5.
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4/25
2/5×2/5.
Write in your own words. A guardian or teacher should review this response.
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2/5×3/4+3/5×2/4=3/5.
Add disjoint orders.
Write in your own words. A guardian or teacher should review this response.
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Actual values within each interval are not supplied.
Explain the missing information.
Progress and browser storage
Notebook challenge, sources and further study
Apply the idea
Compare the same grouped table under two possible individual datasets.
Review with a guardian or teacher
- Use the stated evidence or givens.
- Show reasoning rather than only a result.
- Review and explain one correction.
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