5. Capacity Planning using queuing models (20 points) An IT help desk has a central check-in counter for all customers. Arrivals are assumed to follow the Poisson distribution, with a mean rate of 7 customers per hour (1 = 7). Service times are assumed to follow the exponential distribution. With the current service capacity, the average service time is 5 minutes (u = 12 customers / hi). 1) What is the mean number of customers in service? 2) How many chairs should be provided for those waiting in line if we aim to the goal that people will find a chair to wait 90% of the time? Hint: use formula P = (1-P) p" Calculate cumulative probability till it reaches 90%. See example 12.1 in LEAD notes. n P(number of customers <>