In a Go-Back-N protocol with a sender window of size 4, the frames numbered 1 to 10 are to be sent. Frame 5 is lost on its first transmissi…

In a Go-Back-N protocol with a sender window of size 4, the frames numbered 1 to 10 are to be sent. Frame 5 is lost on its first transmission only, and no other frame or acknowledgement is lost. The sender has transmitted frames 6, 7 and 8 before the timer of frame 5 expires. What is the total number of frame transmissions (including retransmissions) needed to deliver all ten frames?