Assume a FILE of size $S=20$ MBytes. We want to send the file in a path that consists of $20$ routers. Each link through the path has a $8ms$ propagation delay and transmits at a rate of $16Mbps.$ The total number of packets is $6000,$ and the payload is $10000$ bits for each single packet.

a$.$ Find the packet overhead, such that the total end$-$to$-$end delay is equal to $4\mathrm{.}683$ seconds. $($Ignore queuing and processing delay$).(6$ pts$)$

b$.$ Find the total end$-$to$-$end delay if a circuit$-$switched network $($with TDMA of $8$ slots $\frac{?}{sec})$ is considered for the same file. Consider the connection setup requires $200ms$