During the next four quarters, Wivco faces the following demands for globots: quarter 1, 13; quarter 2, 14; quarter 3, 12; quarter 4, 15. Globots can be produced by regular-time labor or by overtime labor. Production capacity (number of globots) and production costs during the next four quarters are shown in the file P16_11.xlsx. Wivco has set the following goals in order of importance:
■ Goal 1: Each quarter’s demand should be met on time.
■ Goal 2: Inventory at the end of each quarter should not exceed three units.
■ Goal 3: Total production cost should be no greater than $250.
Use a goal programming model to determine Wivco’s production schedule for the next four quarters. Assume that at the beginning of the first quarter, one globot is in inventory.