Calculate the total time required to transfer a 1000-kb file in the following cases, assuming an rtt of 50 ms, a packet size of 1 kb data, and an initial 2×rtt of "handshaking" before data is sent: a) the bandwidth is 1.5 mbps, and data packets can be sent continuously. b) the bandwidth is 1.5 mbps, but after we finish sending each data packet we must wait one rtt before sending the next. c) the bandwidth is "infinite," meaning that we take transmit time to be zero, and up to 20 packets can be sent per rtt. d) the bandwidth is infinite, and during the first rtt we can send one packet (2 1−1 ), during the second rtt we can send two packets (2 2−1 ), during the third we can send four (2 3−1 ), and so on.