Lesson P9

P9 calculate and interpret conditional probabilities through representation using... Quiz: Pearson Edexcel Maths, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson P9, calculate and interpret conditional probabilities through representation using...: 20 multiple choice questions for the Pearson Edexcel GCSE Maths (1MA1), Unit 5: Probability, written with Revision Ninja.

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The 20 questions

  1. In conditional probability notation, what does the vertical bar mean in P(A | B)?

    • And
    • Not
    • Given
    • Or

  2. When using expected frequencies in a two-way table for conditional probability, what is the denominator?

    • Column total
    • Row total
    • Condition total
    • Grand total

  3. A table shows: boys 12 like sport and 8 do not; girls 5 like sport and 15 do not. What is P(likes sport | girl)?

    • 0.25
    • 0.2
    • 0.4
    • 0.125

  4. Using the same table (boys: 12 like sport, 8 do not; girls: 5 like sport, 15 do not), what is P(girl | likes sport)?

    • 5/40
    • 5/20
    • 17/20
    • 5/17

  5. 100 people were surveyed. 60 have pets and 30 of the pet owners own dogs. What is P(dog | pet owner)?

    • 0.2
    • 0.5
    • 0.6
    • 0.3

  6. In a group of 50, 30 like tea and 25 like coffee, and 10 like both. What is P(tea | coffee)?

    • 0.3
    • 0.2
    • 0.4
    • 0.5

  7. A card is a heart. What is the probability that it is a king?

    • 1/52
    • 1/13
    • 4/13
    • 1/4

  8. 200 people were tested and 30 tested positive. Of the positives, 27 have the disease. What is P(disease | positive)?

    • 0.9
    • 0.27
    • 0.135
    • 0.15

  9. Which identity holds for conditional probabilities?

    • P(not A | B) = P(A | B)
    • P(not A | B) = 1 − P(A | B)
    • P(not A | B) = 1 + P(A | B)
    • P(not A | B) = P(B | A)

  10. A first draw is red with probability 0.4. Given the first draw is red, the second is red with probability 0.5. What is P(second red | first red)?

    • 0.5
    • 0.9
    • 0.4
    • 0.2

  11. 120 pupils: 40 walk, 50 take the bus and 30 cycle. Of the walkers, 15 are in Year 7. What is P(Year 7 | walks)?

    • 0.125
    • 0.3
    • 0.5
    • 0.375

  12. Set S has 20 elements and 8 of them are in both S and T. Set T has 35 elements. What is P(S | T)?

    • 8/35
    • 8/20
    • 20/35
    • 8/13

  13. P(A) = 0.3, P(B | A) = 0.6 and P(B | not A) = 0.2. What is P(B)?

    • 0.18
    • 0.6
    • 0.14
    • 0.32

  14. P(A) = 0.3 and P(B | A) = 0.6. What is P(A and B)?

    • 0.18
    • 0.9
    • 0.2
    • 0.42

  15. 80 people were surveyed. 50 are bus users and 20 of them are students. There are 30 students in total. What is P(not a student | bus user)?

    • 0.2
    • 0.375
    • 0.6
    • 0.4

  16. P(A | B) = 0.5 and P(B) = 0.4. What is P(A and B)?

    • 0.8
    • 0.1
    • 0.2
    • 0.5

  17. A deck has 10 cards, 4 of which are hearts. The first card is a heart and is not replaced. What is P(second card is a heart)?

    • 1/3
    • 4/10
    • 3/10
    • 2/5

  18. Why are expected frequencies helpful when calculating conditional probabilities from two-way tables?

    • Double the values
    • Restrict to condition
    • Find grand totals
    • Remove all decimals

  19. A group of 500 people has P(A) = 0.2 and P(B | A) = 0.3. What is the expected number with both A and B?

    • 30
    • 150
    • 3
    • 100

  20. P(A) = 0.7, P(not B | A) = 0.1 and P(not B | not A) = 0.5. What is P(B)?

    • 0.63
    • 0.22
    • 0.85
    • 0.78

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