from scipy.stats import poisson
prob_of_15_or_less_occurrences = poisson.cdf(15, 12) # Cumulative density function
We have to find probabilit of more than 15 occurence, so we will substract it from 1
prob_of_more_than_15_occurrences = 1- prob_of_15_or_less_occurrences
prob_of_more_than_15_occurrences