$10\mathrm{.}12.$ Reconsider Problem $10\mathrm{.}11.$ The management of Sunny

Skies Unlimited now has decided that the decision regarding the

locations of the paramedic stations should be based mainly on costs.

The cost of locating a paramedic station in a tract is $$200,000$

for tract $1,$ $$250,000$ for tract $2,$ $$400,000$ for tract $3,$ $$300,000$

for tract $4,$ and $$500,000$ for tract $5.$ Management$$s objective

now is to determine which tracts should receive a station to mini$-$

mize the total cost of stations while ensuring that each tract has

at least one station close enough to respond to a medical emer$-$

gency in no more than $15$ minutes. In contrast to the original

problem, note that the total number of paramedic stations is no

longer fixed. Furthermore, if a tract without a station has more

than one station within $15$ minutes, it is no longer necessary to

assign this tract to just one of these stations.