Suppose Host A wants to send a large file to Host B$.$ The path from Host A to Host B goes through

three links sequentially, of rates $R1=500kbps,R2=2Mbps,$ and $R3=1Mbps.$

Host $A>R1R2$ R $$ R $3$ Host $B$

a$.$ Assuming no other traffic in the network, what is the throughput for the file transfer?

Please show your work.

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$?$Please show vour work.