Problem GBC Systems manufactures rugged handheld computers for use in adverse working environments. GBC tries to maintain inventory at 20% of the following month's expected unit sales. GBC began the year with 2,000 units in stock, based on the following unit sales projections prepared by the sales manager January 25,000 February 24,000 March 19,000 April 23,000 Prepare a schedule of planned unit production for January through March