Problem $1(20$ points$).$ Consider figure $1,$ where the sender transmits one packet of size L $=1$ KB $($kilobytes$).$ The link speeds are R$1=$ R$2=$ R$3=1$ Mbps $($megabits per second$).$ The length of each link is $100$ Km$.$ Compute the end$-$to$-$end delay for the following situations. We assume that the propagation speed of the packet is $20,000$ Km$/$s$,$ and that the processing time of the packet at each router is $5\backslash$mu s$.$