n a message$-$switched network, the probability density function of the message

size is exponential, with an average message size of $0\mathrm{.}8$ Mbit. At a particular

node in the network, the arrival of messages can be modelled as a Poisson

random process, with an average rate of $100$ message$/$s$.$ Of those messages,

$20\%$ queue for transmission on a particular outgoing link. The average time

that a message spends in that queue, including time spent being transmitted, is

$40$ ms$.$ What is the throughput of that link, in Mbit$/$s