Poisson Distribution
Assume that there is X cars passing in anhour.
X= 60 mins/hour * X/60 per mins
P(x=k)= choose k from 60 * (x/60)^k *(1-x/60)^60-k
And if you want to be more precise, you canmake unit of time to be seconds, then
P(x=k)=choose k from 3600*(x/60)^k *(1-x/3600)^3600-k
Then you get it, Wallace : )
