(a) host - router ,then router - router,then router to destination
so,in total 3 hops for a packet.
(b) mean number of transmissions -
it might be possible that there is only 1 transmission i.e packet is nt dropped by any router.
or it might be the case that in first transmission,packet is dropped by a router,so again source will start transmission,hence 'p' this time
in this way 1+ p + p*p + p*p*p +........
so,mean number of transmissions are (1/1-p)
please correct me