 Solution

ID: past-exam-of-the-options-ii-course-of-the-university-of-oxford/2012/m/m5/a/solution

Since

N_{3} \sim Poisson (3 λ)

P (N_{3} \geq 1) = 1 - P (N_{3} = 0) = 1 - e^{- 3 λ} .

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