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0580/31 Oct/Nov 2025, Question 7: Basic Probability

Cambridge IGCSE Mathematics 0580 · Paper 31 (Core) · Calculator · 3 marks

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The question, in short

A bag holds 6 red, 4 green and 2 blue balls; Zia picks one at random. Using a 0-to-1 probability scale with arrows A to G, identify which arrow matches each stated probability.

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

Part (a) · 1 mark

Find which arrow on the scale represents the probability of taking a green ball.

  1. 1P(green) = 4/12 = 1/3
  2. 2The arrows are at 0, 1/6, 2/6, …, 1, so 1/3 = 2/6 is arrow C

AnswerC

Part (b) · 1 mark

Find which arrow on the scale represents the probability of taking a yellow ball.

  1. 1There are no yellow balls, so P(yellow) = 0
  2. 2Arrow A

AnswerA

Part (c) · 1 mark

Find which arrow on the scale represents the probability of not taking a blue ball.

  1. 1P(not blue) = 10/12 = 5/6
  2. 25/6 is arrow F

AnswerF

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