During the morning hours customers arrive at Starbucks for c

During the morning hours, customers arrive at Starbucks for coffee at an average rate of 90, per hour (Poisson), while employees can serve customers at an average time (exponential) of 3 minutes each. Find: Minimum number of servers to schedule

Solution

90 in 60 mins. i.e. 1.5 customers per min = 4.5 customers per 3 min

3 mins for one server

i.e if 4.5 servers per 3 min are required at once

Hence 4.5 servers will do the work

Since 4.5 is not possible so answer is 5