Final answer:
To determine the optimal number of days each mine should operate, we can use linear programming to solve for the minimum total cost while fulfilling Universal Mines' commitment.
Step-by-step explanation:
To determine the number of days each mine should operate, we need to find the optimal solution that fulfills Universal Mines' commitment at the minimum total cost. Let's use linear programming to solve this problem.
Let xi be the number of days Mine i should operate, where i ranges from 1 to 3.
Minimize the total cost: 20,000x1 + 22,000x2 + 18,000x3
Subject to the following constraints:
4x1 + 6x2 + x3 ≥ 54 (for high-grade ore)
4x1 + 4x2 + 6x3 ≥ 65 (for low-grade ore)
x1, x2, x3 ≥ 0 (since the number of days cannot be negative)
By solving this linear programming problem, we can find the optimal number of days each mine should operate to fulfill the commitment at the minimum total cost.