A crossbar exchange is required to set up 5000 calls in the busy hour.The marker holding times may be assumed to be exponentially distributed,with an average holding time of 0.5 second.
a)find the number of markers required, if the probability ofa register having to wait for a marker is to be less than 0.2
b)what will happen if a local crisis causes 25000 calls to originate in the busy hour?