Final answer:
Using queuing theory and given an arrival rate of 10 patients per hour and a service rate of 18 patients per hour, the average number of patients in the system at any given time is calculated to be 1.25. This is based on the M/M/1 queue model.
Step-by-step explanation:
When calculating the number of patients in a system like an eye care clinic where arrivals and services both follow exponential distributions, we use queuing theory. Given the arrival rate (λ) is 10 patients per hour and the service rate (μ) is 18 patients per hour, we can apply the formula L = λ / (μ - λ) for the average number of patients in the system (L). For our data, L = 10 / (18 - 10) = 10 / 8 = 1.25. Therefore, on average, 1.25 patients will be in the system at any given time, which includes both the patients being served and those waiting. This scenario is a classic example of an M/M/1 queue, a basic model in queuing theory in which arrivals are described by a Poisson process, service times are exponentially distributed, and there is one server.