Final answer:
The utilization at the bank teller's window is 33%.
Step-by-step explanation:
The utilization at the bank teller's window can be calculated by dividing the average service rate by the arrival rate. In this case, the average service rate is 1 customer every 4 minutes and the arrival rate is 45 customers per hour. To find the arrival rate per minute, we divide 45 by 60, which equals 0.75 customers per minute. Now we can calculate the utilization by dividing the average service rate (0.25 customers per minute) by the arrival rate per minute (0.75 customers per minute). The utilization is therefore 0.25 / 0.75 = 0.33 or 33%.