So if we use Poisson Distribution we will get the following formula: P(x) = 11x x e^-11/x! where 'x' is the number of days in precipitation. a) What is the probability of having exactly 10 days of precipitation in the month of April? P(x=10) which would be 12^10 x e^-14/10! which equals b) What is the probability if we have less than 3 days of precipitation in April? P(x15) = 1-P(x