Customers arrive at photocopying machine at an average rate of 2 each 5 minutes. Assume that this arrivals are independent, with a constant arrival rate and hat thi sproblem follows a poisson distributionn, with X denoting the number of arrivals in a 5 minute period and mean lambda=2. Find the probab that more than 2 customers arrive in a 5 minute period.

This is no problem to solve. I just want to see if I got Poisson well. Like, 5 is my time base, right. So I know, that 2 persons come each 5 minutes. So people are computed on a base(subinterval) of 5 minutes. So if they ask me the prob that more than 2 customers arrive in a 1 minute period I should do

2: 5= x:1 x=2/5=0.4 and my lambda would be 0.4

so P=1 - P(0) - P(1) -P(2)

right?? Thank you so much