Please help me understand these questions. I got as far as A and B. Please show your work and let me know if I did a and b correctly. Thank you

The Bijou Theater shows vintage movies. Customers arrive at the theater line at the rate of 75 per hour. The ticket seller averages 32 seconds per customer, which includes placing validation stamps on customers' parking lot receipts and punching their frequent watcher cards. (Because of these added services, many customers don't get in until after the feature has started.) (Use the Excel spreadsheet Queue Models.) a. What is the average customer time in the system? (Round your answer to 2 decimal places.) Average customer time 0.03 minutes b. What would be the effect on customer time in the system of having a second ticket taker doing nothing but validations and card punching, thereby cutting the average service time to 20 seconds? (Round your answer to 3 decimal places.) Average time in system 0.010 minutes c. What would be the customer time in the system if instead of the change in Part b, a second window was opened with each server doing all three tasks? (Do not round intermediate calculations. Round your answer to 3 decimal places.) Average time in system | minutes d. Would system waiting time which is obtained in part (c) be less than you found in (b)? Yes