Spencer Electric ships 12,000 capacitors per month to its customers. The capacitors can be produced at three different plants. The production capacity, fixed monthly cost of operation, and variable cost of producing a capacitor at each plant are given in the file P06_66.xlsx. The fixed cost for a plant is incurred only if the plant is used to make any capacitors. If a plant is used at all, at least 3000 capacitors per month must be produced at the plant. Determine how to minimize the company’s monthly costs of meeting its customers’ demands.