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.