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O-LevelMathematicsProbability4024/12 · Oct/Nov 2019 · Q173 Marks

A bag contains two white beads and one black bead only. Two beads are taken, at random, without replacement from the bag. [Figure X.X]

  1. (a)Complete the tree diagram.[2]
  2. (b)Write down the probability that two black beads are taken.[1]

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Mark scheme

Marking points from the official mark scheme (Oct/Nov 2019). The mark or mark type is shown in brackets.

  1. [2] (a) Correct tree diagram with four branches added and the five correct probabilities 2/3, 1/2, 1/2, 1, [0] B1 for at least two second branches drawn and 2 or 3 probabilities completed correctly
  2. [1] (b) 0

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About this question

Topic
Probability, O-Level Mathematics (syllabus 4024). Structured question, 3 marks.
Source
O-Level Mathematics, Oct/Nov 2019 Paper 1 Variant 2, question 17.

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