A self-service car wash has 3 individual car wash stalls. Customers wait in a single line before choosing the next available stall. 33 customers enter the car wash per hour and it takes 5 minutes for each customer to wash their car. Customer arrivals and service times follow an exponential distribution.How many customers on average are waiting in line?Round to the nearest whole number. Within your calculations, do not round to fewer than 4 decimal places.
A. 4
B. 8
C. 9
D. 6