A few points about FTP
1. FTP initiates a new TCP connection for each file transfer. Users can observe this in Packet trace.
2. Since file size is more than the Transport layer MSS, the file gets fragmented into packets of size 1460B
The per-file throughput for each file of the FTP application can be calculated from the trace as:
Per file throughput = BytesReceived successfully at destination / (TCP-Connection-End-Time - TCP-Connection-Start-Time)
TCP-Connection-End-Time is when the ACK for the FIN is received
TCP-Connection-Start-Time is when the when the SYN is sent
This throughput is one definition and slight modifications whereby the times of the last packet & first packets (instead of TCP SYN / ACK) can also be used for throughput calculation