poisson distribution example

If the mean rate of arrival in a restaurant is 10 customers per hour, what is the probability of having 4 customers arriving in any hour?

P(4) =10ˆ4 eˆ-10 / 4!
= 0.0000454 X 10000/24

but 0.0000454 this number seem wrong for me

and if we reduce the arrival on 10 minutes we get :
10X10/60 =1.67
P(4in 10 min)= eˆ1,67/4!
and where the 7.72 comes from ?


Active Member
OK. Got it. In that case, the second calculation is right too. The 7.72 is 1.67^4. Each calculation has three bits e^rate, rate^number, and factorial number.