X follows Poisson distribution,

X = Poisson(λ)

, how to calculate λ if we know the probability of x being 3 or less is 0.82, that is

cdf(X,3) = 0.82

. is there any syntax or solver?

X follows Poisson distribution,

X = Poisson(λ)

, how to calculate λ if we know the probability of x being 3 or less is 0.82, that is

cdf(X,3) = 0.82

. is there any syntax or solver?

You can use `find_zero`

in Roots.jl to solve this:

```
julia> using Distributions, Roots
julia> find_zero(λ -> cdf(Poisson(λ), 3) - .82, 2)
2.1967047830443853
```

3 Likes

thank you