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2.3 Probability

2.3 Probability

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Question 76

An ecological survey analyzed 150 specific woodland plots to identify the presence of three rare fungal species: Amanita (AAA), Boletus (BBB), and Clitocybe (CCC). The findings were as follows:

  • 82 plots contained Amanita
  • 68 plots contained Boletus
  • 54 plots contained Clitocybe
  • 38 plots contained both Amanita and Boletus
  • 28 plots contained both Boletus and Clitocybe
  • 32 plots contained both Amanita and Clitocybe
  • 18 plots contained all three species
a.

Draw a Venn diagram to represent these data.

[4]
b.

Find the probability that a randomly selected plot from the survey:

contains none of these fungal species,

[1]
c.

contains Boletus but does not contain Amanita,

[2]
d.

contains at least two of these species.

[2]
e.

One plot is selected at random and is found to contain Amanita.

Find the probability that this plot also contains Boletus but does not contain Clitocybe.

[3]
Markscheme

2.3 Probability Questions

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

200 exam-style questions on OCR (MEI) A Level Maths 2.3 Probability, covering 2.3.1 Calculate the probability of an event, 2.3.2 Complementary events, 2.3.3 Expected frequency of an event, 2.3.4 Diagrams to calculate probabilities, 2.3.5 Mutually exclusive and independent events, 2.3.6 Add probabilities for mutually exclusive events, 2.3.7 Multiply probabilities for independent events, 2.3.8 Mutually exclusive and independent events (notation) (A-level only), 2.3.9 Venn diagrams for probabilities (A-level only), 2.3.10 Conditional probabilities (A-level only), and 2.3.11 Independence via conditional probability (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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