In large cities, hospital administrators worry about the question of human trafficking in hospital emergency rooms. for a hospital specific in a large city, the available staff cannot accommodate the traffic of patients when there are more than 10 emergency cases in a given hour. Be supposed to patient arrival follows a Poisson process and historical data suggest that, On average, 5 emergencies arrive every hour. 1- What is the probability that in a given hour the staff cannot accommodate more to traffic? 2- What is the probability of waiting more than 20 minutes between any two successive emergency arrivals?