I'm trying to prepare for my Stohastic Processes exam, and i couldn't solve one of exercises. The exercise is as follows:
Costumers arrive to the store according to the Poisson process $N_t$ with rate $4$ and spend time there uniformly distributed on [0, 2] (independent of other people and $N_t$). Find the probability that at the moment $t=5$ there will be 3 costumers.
Help me understand the direction in which i need to solve this problem please.