Huck and jim are waiting for a raft. the number of rafts floating by over intervals of time is a poisson process with a rate of λ = 0.4 rafts per day. they agree in advance to let the first raft go and take the second one that comes along. what is the probability that they will have to wait more than a week? hint: if they have to wait more than a week, what does that say about the number of rafts in a period of 7 days?