9.4-3. The Premiere Bank soon will be hooking up computer ter- minals at each of its branch offices to the computer at its main of- fice using special phone lines with telecommunications devices. The phone line from a branch office need not be connected directly to the main office. It can be connected indirectly by being con- nected to another branch office that is connected (directly or indi- rectly) to the main office. The only requirement is that every branch office be connected by some route to the main office. The charge for the special phone lines is $100 times the num- ber of miles involved, where the distance (in miles) between every pair of offices is as follows: Distance between Pairs of Offices Main B.1 B.2 B.3 B.4 B.5 Main office 190 70 115 270 160 Branch 1 190 100 110 215 50 Branch 2 70 100 140 120 220 Branch 3 115 110 140 175 80 Branch 4 270 215 120 175 310 Branch 5 160 50 220 80 310 Management wishes to determine which pairs of offices should be directly connected by special phone lines in order to connect every branch office (directly or indirectly) to the main office at a mini- mum total cost. (a) Describe how this problem fits the network description of the minimum spanning tree problem. (b) Use the algorithm to solve the