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1/15
2/6×1/5=1/15.
Class 10 · English Medium · Cambridge · Mathematics
Data, probability and written reasoning
Read probability trees and assess data comparisons.
About this lesson and its coverage
Original Kidemy Class 10 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
Without replacement, later branch probabilities depend on earlier draws. Multiply probabilities along a path and add disjoint paths. A data comparison needs consistent definitions and sampling, not only a large number of observations.
Worked example
From3 red and 2 blue balls, P(two red without replacement)=3/5×2/4=3/10.
- 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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2/5
4/6×3/5=2/5.
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7
84/12.
Write in your own words. A guardian or teacher should review this response.
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They are mutually exclusive orders covering that event.
Use disjoint paths, not overlapping events.
Write in your own words. A guardian or teacher should review this response.
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Those who choose to respond may differ systematically from those who do not.
Explain the selection process.
Progress and browser storage
Notebook challenge, sources and further study
Apply the idea
Draw a two-step tree and explain the result in words, including its assumptions.
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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