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2.3 Probability

2.3 Probability

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Question 39

A farmer plants three varieties of tomato seeds: Variety A, Variety B, and Variety C. Variety A makes up 35% of the crop, Variety B makes up 45%, and Variety C makes up 20%.

The probability that a seed fails to germinate is:

  • 2.5% for Variety A
  • 1.5% for Variety B
  • 5.0% for Variety C
a.

Draw a tree diagram to show this information.

[3]
b.

A seed is selected at random. Find the probability it fails to germinate.

[2]
c.

Given that a seed failed to germinate, find the probability it was Variety B.

[3]
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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