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2.3 Probability

2.3 Probability

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Question 40

Two sacks, P P\,P and QQQ, contain gold, silver, and bronze discs. Sack P P\,P contains 5 gold discs, 2 silver discs, and 1 bronze disc. Sack Q Q\,Q contains 3 gold discs, 4 silver discs, and 5 bronze discs. Alex picks one disc at random from Sack P P\,P and places it into Sack QQQ. Alex then picks one disc at random from Sack QQQ.

a.

Draw a tree diagram to represent this information.

[2]
b.

Find the probability that Alex picks two discs of the same colour.

[2]
c.

Given that both discs are the same colour, find the probability they are both gold.

[2]
Markscheme

2.3 Probability Questions

  1. A Level
  2. /Maths
  3. /2.3 Probability

200 exam-style questions on OCR A Level Maths 2.3 Probability, covering 2.3.1 Mutually exclusive and independent events, 2.3.2 Diagrams to assist probability calculations, 2.3.3 Conditional probability (A-level only), 2.3.4 Conditional probability from first principles (A-level only), and 2.3.5 Modelling with probability. Each one has a worked solution and a mark scheme showing where the marks go.

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