Calculate the total time required to transfer a $1\mathrm{.}5-$MB file in the following cases, assuming anRTT of $80$ ms$,$ a packet size of $1$ KB data, and an initial $2\backslash$times RTT of handshaking before data issent:$($a$)$ The bandwidth is $10$ Mbps$,$ and data packets can be sent continuously.$($b$)$ The bandwidth is $10$ Mbps$,$ but after we finish sending each data packet we must wait oneRTT before sending the next.$($c$)$ The link allows infinitely fast transmit, but limits bandwidth such that only $20$ packets can besent per RTT