Lesson 2.04a

2.04a Discrete distributions Quiz: OCR Maths, Unit 14

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 2.04a, Discrete distributions: 20 multiple choice questions for the OCR Maths (H240), Unit 14: Statistical Distributions, written with Revision Ninja.

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The 20 questions

  1. What must all probabilities in a discrete probability distribution sum to?

    • 100
    • 0
    • Infinity
    • 1

  2. Which variable is classified as discrete rather than continuous?

    • Number of goals
    • Mass of ball
    • Height of player
    • Time taken

  3. What probability expression is shown alongside each outcome x in a discrete probability distribution table?

    • P(X < x)
    • P(X ≠ x)
    • P(X = x)
    • P(X > x)

  4. What is the sum of all probabilities P(X = x) in a valid discrete probability distribution?

    • 100
    • 1
    • 0
    • 0.5

  5. Given P(X = x) = 0.05x(x + 1) for x = 1, 2, 3, what is P(X = 2)?

    • 0.2
    • 0.1
    • 0.3
    • 0.6

  6. What term describes an outcome with a probability of zero in a statistical model?

    • Probable
    • Unlikely
    • Certain
    • Impossible

  7. What is the term for the set of all possible outcomes of an experiment?

    • Population
    • Event space
    • Probability set
    • Sample space

  8. A distribution has P(X = 0) = 0.2, P(X = 1) = 0.5 and P(X = 2) = 0.3. What is P(X >= 1)?

    • 0.2
    • 0.5
    • 0.8
    • 0.3

  9. P(X = x) = kx for x = 1, 2, 3, 4 is a probability distribution. What is k?

    • 0.25
    • 1
    • 0.2
    • 0.1

  10. Using the distribution P(X = x) = 0.1x for x = 1 to 4, what is P(X <= 2)?

    • 0.4
    • 0.3
    • 0.6
    • 0.7

  11. A discrete distribution on x = 1, 2, 3, 4 has P(X = 1) = 0.1, P(X = 2) = 0.4 and P(X = 4) = 0.2. What is P(X = 3)?

    • 0.1
    • 0.6
    • 0.7
    • 0.3

  12. P(X = x) = 0.2 for x = 1, 2, 3, 4 and 5. What is P(X >= 4)?

    • 0.6
    • 0.2
    • 0.4
    • 0.8

  13. Two fair dice are rolled and their sum is recorded. What is P(sum = 12)?

    • 1/11
    • 1/12
    • 1/6
    • 1/36

  14. A sample of 2 items is checked for defects. P(0) = 0.7, P(1) = 0.25 and P(2) = 0.05. What is P(at least one defective)?

    • 0.7
    • 0.05
    • 0.3
    • 0.95

  15. A discrete random variable has probabilities 0.2, 0.3, and k. What is the value of k?

    • 0.5
    • 0.6
    • 0.8
    • 0.1

  16. P(X = x) = a(6 - x) for x = 1, 2, 3, 4, 5. What is a?

    • 1/15
    • 1/6
    • 1/21
    • 1/5

  17. For the same distribution P(X = x) = a(6 - x), what is P(X > 2)?

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

  18. P(X = x) is proportional to x for x = 1, 2 and 3, and zero otherwise. What is P(X = 3)?

    • 1/6
    • 1/2
    • 3/5
    • 1/3

  19. A distribution has P(X = x) = c x 2^x for x = 0, 1 and 2. What is P(X = 2)?

    • 2/7
    • 1/7
    • 4/7
    • 1/4

  20. A distribution has P(X = 0) = 0.3, P(X = 1) = 0.4, P(X = 2) = p and P(X = 3) = 0.1. What is p?

    • 0.15
    • 0.6
    • 0.25
    • 0.2

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