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2.3.3 Conditional probability (A-level only)

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Question 34

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

2.3.3 Conditional probability (A-level only) Questions

  1. A Level
  2. /Maths
  3. /2.3.3 Conditional probability (A-level only)

116 exam-style questions on OCR A Level Maths 2.3.3 Conditional probability (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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