Answer:
3 customers
Step-by-step explanation:
Rate of arrival (λ) = 15 per hour
Service rate (μ) = 20 per hour
The number of customers in a system given the arrival rate and the mean service rate is given by:
[tex]N = \frac{\lambda}{\mu-\lambda}\\[/tex]
Applying the given data:
[tex]N = \frac{15}{20-5}\\N=3\ customers[/tex]
The average number of customers in the system is 3 customers.