Carry out course work. The Internet did not find the answer to your question.
You need to combine the 4 buildings into a single LAN. Building 1 from building 2 to be removed on the 1 km building 2 from building 3 to be removed on 200 m, the building 4 building 3 to be removed on the 10 km. - a provider of the Internet on distance of 5 km to Lay cable ducts between the buildings is impossible. And the desired data transfer rate Internet 50 Mbit/s.
In buildings, the network held. I just don't know how to connect the building with large distance. Between buildings 2 and 3 you can use Wi-Fi, and how to deal with the other buildings I do not know. Perhaps satellite Internet, Wi-Fi is unlikely to pass 10 km.