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2.3 Probability

2.3 Probability

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Question 135

The probability that Sarah travels to her office by train, by bus, or by car is 35\frac{3}{5}53​, 14\frac{1}{4}41​, and 320\frac{3}{20}203​ respectively. The probability of being late to work when using these methods of travel is 112\frac{1}{12}121​, 15\frac{1}{5}51​, and 13\frac{1}{3}31​ respectively.

a.

Draw a tree diagram to represent this information.

[2]
b.

Find the probability that on a randomly chosen day: (i) Sarah travels by car and is late, (ii) Sarah is not late.

[3]
c.

Given that Sarah is late, find the probability that she did not travel by train.

[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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