A small post office has two open windows. Customers arrive according to a Poisson distribution at the rate of 1 every 3 minutes. However, only 80% of them seek service at the windows. The service time per customer is expoenential, with a mean of 5 minutes. All arriving customers form one line and access available windows on an FCFS basis.
a) What is the probability that an arriving customer will wait in line?
Here is what I do know:
Servers c=2
Arrival Rate 20 customers per hour, 80% seek service
Lambda=16 customers per hour
Service Rate: mu= 12 customers per hour
Probability of arriving customer can enter 1 of 3 spaces=P[n<=2] (if there are 3 people, the line is full, so must be 2 or less people)