MINIMIZING CITY WATER COSTS The water-supply manager for a Midwestern city needs to supply the city with at least
10
million gallons of potable (drinkable) water per day. The supply may be drawn from the local reservoir or from a pipeline to an adjacent town. The local reservoir has a maximum daily yield of
5
million gallons of potable water, and the pipeline has a maximum daily yield of
10
million gallons. By contract, the pipeline is required to supply a minimum of
6
million gallons/day. If the cost for
1
million gallons of reservoir water is
$
300
and that for pipeline water is
$
500
, how much water should the manager get from each source to minimize daily water costs for the city? What is the minimum cost?