An Oil Company Operates Two Refineries in a Certain City

Multiple Choice

An oil company operates two refineries in a certain city. Refinery I has an output of 200, 100, and 100 barrels of low-, medium-, and high-grade oil per day, respectively. Refinery II has an output of 100, 200, and 600 barrels of low-, medium-, and high-grade oil per day, respectively. The company wishes to produce at least 1,000, 1,400, and 3,000 barrels of low-, medium-, and high-grade oil to fill an order. If it costs $500/day to operate refinery I and $700/day to operate refinery II, determine how many days each refinery should be operated to meet the requirements of the order at minimum cost to the company. What is the minimum cost?

A) refinery I for 0 days; refinery II for 10 days; $5,300
B) refinery I for 6 days; refinery II for 4 days; $5,400
C) refinery I for 2 days; refinery II for 6 days; $5,200
D) refinery I for 3 days; refinery II for 5 days; $5,200