CAIE A-Level Mathematics 6.1.2 The fact that if X Po+

CAIE A-Level Mathematics 6.1.2 The fact that if X Po+
Cambridge International AS & A Level Mathematics 9709 syllabus for exams in 2028, 2029 and 20302028–2030

Practise using the Poisson fact that the mean and variance are both λ when interpreting or forming a count distribution.

How this is tested

  • use E(X)=λ and Var(X)=λ when a variable is given as Po(λ)

Question 2(a)

[Maximum number: 1]

The random variable W has a Poisson distribution.
State the relationship between E(W) and Var⁡(W)\operatorname{Var}(W).