to a full availability group in a delay system consisting of $30$ devices is offered a traffic with the calling rate $700$ calls$/$hour and the mean holding time

$108$sec

$.$ Supposing the assumptions for the Erlang distribution for delay systems to be fulfilled, calculate a$)$ The traffic offered. b$)$ The probability of delay. c$)$ The traffic handled. d$)$ The mean of the traffic handled per device. e$)$ The mean waiting time for all calls. f$)$ The mean waiting time for calls, which have to wait.