Phone calls are received at Janice’s house according to a Poisson Process with parameter λ=2 per hour.
How long can Janice’s shower be if she wishes the probability of receiving no phone calls to be at most 0.5?
What I have tried: Substituted λt in the poisson formula with x = 0 which should be less than 0.5. Should I be taking log on both sides?
The answer is 20 minutes - how?