Chapter 4.CRE, Problem 23CRE

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?