Example 3 Two one man barber shops sit side by side at Pacific Mall. Each can hold a maximum of 4 customers, and any potential customer who finds a shop full will not wait for a haircut. Barber 1 takes an average of 12min and Barber 2 takes an average of 5min. An average of 10 potential customers /hr arrive at Barber 1 and 12/hr arrive at Barber 2. Assuming that the number of arrivals is Poisson distributed and hair cut times is exponential, which barber shop will more likely to be full when you arrive for a hair cut