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2.3 Probability

2.3 Probability

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Question 74

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 (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.

Question bank