Based on Eaton et al. (1985). The city of Springfield has been divided into eight districts. The time (in minutes) it takes an ambulance to travel from one district to another is shown in the file P06_78.xlsx. The population of each district (in thousands) is as follows: district 1, 40; district 2, 30; district 3, 35; district 4, 20; district 5, 15; district 6, 50; district 7, 45; district 8, 60. Suppose Springfield has n ambulance locations. Determine the locations of ambulances that maximize the number of people who live within two minutes of an ambulance. Do this separately for n = 1; n = 2; n = 3; n = 4. (Set it up so that SolverTable can solve all four problems simultaneously.)