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0580/12 May/Jun 2026, Question 22: Tree Diagrams for Independent Events

Cambridge IGCSE Mathematics 0580 · Paper 12 (Core) · Non-calculator · 4 marks

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The question, in short

A bag holds 7 pink and 5 green blocks; Kay picks one, replaces it, then picks again. Complete the tree diagram and find the probability both picks are green.

Summarised in our own words. Use the official paper for the exact wording and the diagram.

Part (a) · 2 marks

Fill in the missing fractions on the two-stage tree diagram for picking a block twice with replacement.

  1. 1There are 12 blocks: P(pink) = 7/12, P(green) = 5/12
  2. 2The block is replaced so the probabilities are the same on the second pick

AnswerFirst green 5/12; after pink: pink 7/12, green 5/12; after green: green 5/12

Part (b) · 2 marks

Using the completed tree diagram, calculate the probability that both selected blocks are green.

  1. 1P(green, green) = 5/12 × 5/12
  2. 2= 25/144

Answer25/144

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Also searched as: 0580/12/M/J/26 · 0580_s26_qp_12 · 0580 s26 12 · question 22.
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