An office employs several clerks who create documents and has one operator who enters the document information in a computer system. The group creates documents at a rate of 18 per hour. The operator can enter the information with an average exponentially distributed time of 2.5 minutes. Assume the population is infinite, arrivals are Poisson, and queue length is infinite with FCFS discipline. a. Calculate the percentage utilization of the operator. (Round your answer to 2 decimal places.) b. Calculate the average number of documents in the system. (Round your answer to 1 decimal place.) c. Calculate the average time in the system. (Round your answer to 1 decimal place.) 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.)