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2.3 Probability

2.3 Probability

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Question 144

A conference organizer surveyed 40 attendees regarding their participation in the Keynote speech and the Technical Workshop. He found that, of the 40 attendees:

  • 25 attended the Keynote speech
  • 16 attended the Technical Workshop
  • 10 attended both the Keynote and the Workshop
a.

An attendee is chosen at random from the 40 surveyed. Determine whether the event 'the attendee attended the Keynote speech' and the event 'the attendee attended the Technical Workshop' are independent.

[2]
b.

For a regional library network, it is known that:

  • the probability that a registered user borrows an e-book is P(E)=25P(E) = \frac{2}{5}P(E)=52​
  • the probability that a registered user borrows an audiobook is P(A)=37P(A) = \frac{3}{7}P(A)=73​
  • the probability that a registered user borrows an audiobook given that they borrow an e-book is P(A∣E)=14P(A|E) = \frac{1}{4}P(A∣E)=41​

Calculate the probability that a registered user borrows an e-book or an audiobook or both.

[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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