219. Suppose Host A wants to send a large file to Host B. The path from Host A to Host B has three links, of rates R1=500kbps,R2=2Mbps, and R3=1Mbps. a. Assuming no other traffic in the network, what is the throughput for the file transfer? b. Suppose the file is 4 million bytes. Dividing the file size by the throughput, roughly how long will it take to transfer the file to Host B ? c. Repeat (a) and (b), but now with R2 reduced to 100kbps