Answer: 0.0001
It is unlikely to have a month with no aircraft accidents .
Step-by-step explanation:
Given : Mean number of aircraft accidents = 9 per month
The Poisson distribution formula :-
, where
is the mean of the distribution.
If X = the number of aircraft accidents per month, then the probability that in a month, there will be no aircraft accidents will be :-

Hence, the probability that in a month, there will be no aircraft accidents = 0.0001
Since this is less than 0.5 , therefor it is unlikely to have a month with no aircraft accidents .