A seven-story office building has 15 adjacent offices per floor. Each office contains a
wall socket for a terminal in the front wall, so the sockets form a rectangular grid in
the vertical plane, with a separation of 4 m between sockets, both horizontally and
vertically. Assuming that it is feasible to run a straight cable between any pair of
sockets, horizontally, vertically, or diagonally, how many meters of cable are needed
to connect all sockets using
(a) A star configuration with a single router in the middle?
(b) A classic 802.3 LAN?