Final answer:
To determine the method with the lowest cost, consider the cost of machines and labor. Method 3 should be chosen as it has the lowest total cost.
Step-by-step explanation:
To determine the total cost of the three methods, you need to consider the cost of machines and labor. If the cost of machines increases to $55 and the cost of labor stays at $40, the total cost for each method can be calculated as follows:
- Method 1: 10 x $55 (machines) + 3 x $40 (labor) = $550 (machines) + $120 (labor) = $670
- Method 2: 7 x $55 (machines) + 3 x $40 (labor) = $385 (machines) + $120 (labor) = $505
- Method 3: 3 x $55 (machines) + 3 x $40 (labor) = $165 (machines) + $120 (labor) = $285
Based on the new total cost, the firm should choose Method 3, as it has the lowest cost of $285.