A queueing system has one single server workstation that admits an infinitely long queue. The rate of arrival of jobs to the queueing system follows the Poisson distribution with a mean of $5$ jobs/hour. The service time of the server is exponentially distributed with a mean of $6$ minutes. In steady state operation of the queueing system, the probability that the server is not busy at any point in time is
- $0.20$
- $0.17$
- $0.50$
- $0.83$