$4.$

Tech wants to develop an area network that will connect its server at its computer and satellite center with the main campus buildings to improve Internet service. The cable will be laid primarily through existing electrical tunnels, although some cable will have to be buried underground. The following network shows the possible cable connections between the computer center at node $1$ and the various buildings, with the distances, in feet, along the branches:

Determine a minimal spanning tree network that will connect all the buildings and indicate the total amount of cable that will be needed to do so$.$