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2.3 Probability

2.3 Probability

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Question 66

A botanical researcher is studying a large population of orchids. In this population, 15%15\%15% of the orchids exhibit the rare "Purple" phenotype (PPP) and the remaining 85%85\%85% exhibit the standard "White" phenotype (WWW). The researcher selects two orchids at random from this population for genetic testing.

a.

Calculate the probability that both selected orchids exhibit the same phenotype.

[2]
b.

Determine the probability that both orchids are Purple, given that at least one of the orchids is found to be Purple.

[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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