Use the following to answer the next 5 questions: a simple queueing system (one server) has a Poisson arrival distribution and exponential service distribution. Customers arrive to the queue at a rate of 6 per hour and the server takes an average of 4 minutes. Question 18 What is the probability exactly three customers will arrive in the next hour? 33% 60% 0.2% O 40% O 37.5% 50% 25% 8.9%