please help

4. (30 points) Iobs arrive according to a Poisson process with rate A = 8/10. There is a single server with an infinite capacity waiting area. Jobs are served in the order of their arrival. The service time of a job is either 0 or b ,>, 1. The probability of a job's service time being b is l/b. A job with service time 0 remains in the system until reaching the server, but then immediately leaves. Service times are mutually independent and independent of the arrival process. (a) What proportion of the time is the server idle? (b) Please compute Wq where Wq is the long run average time that a job waits until service starts. (c) Please compute L where L is the long run average number of jobs in the system