CAIE A-Level Mathematics A2 6.1.2 The Fact That If X Po Questions
Practise using Poisson mean and variance relationships to calculate spread and standard deviation.
- Syllabus
- 2028–2030
- Course
- Mathematics 9709
- Level
- A2
Exam points
- State that the mean and variance of a Poisson variable are exactly equal, using E(X) = Var(X).
- Calculate a Poisson standard deviation as the square root of the stated mean, giving an exact value or requested accuracy.
CAIE A-Level Mathematics A2 6.1.2 The Fact That If X Po Questions question 1
[Maximum number: 1]
The random variable W has a Poisson distribution.
State the relationship between E(W) and Var(W).
B1: E(W) = Var(W).
Allow “they are the same”, or equivalent. Must be =, not ≈ (and not both = and ≈).
Condone E(W) = λ and Var(W) = λ.
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