The last question is in percentage. Thank you in advance.

An office employs several clerks who create documents, and one operator who enters the document information in a computer system. The group creates documents at a rate of 12 per hour. The operator can enter the information with an average exponentially distributed time of 4 minutes. Assume the population is infinite, arrivals are Poisson, and queue length is infinite with the FCFS discipline. a. Calculate the percentage utilization of the operator. (Round your answer to 2 decimal places.) Utilization of the operator % b. Calculate the average number of documents in the system. (Round your answer to 1 decimal place.) Average number of documents c. Calculate the average time in the system. (Round your answer to 1 decimal place.) Average time in system minutes d. Calculate the probability of four or more documents being in the system. (Round your intermediate calculations to 3 decimal places and final answer to 1 decimal place