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2.3 Probability

2.3 Probability

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Question 76

A quality control inspector examines a batch of precision components. The probability that a component is 'Grade-A' (AAA) is 0.25, and the probability it is 'Grade-B' (BBB) is 0.75. The inspector selects two components at random, one after the other, with the first being replaced before the second is drawn.

a.

Calculate the probability that both components are of the same grade.

[2]
b.

Find the probability that both components are Grade-A, given that at least one of the components is Grade-A.

[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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