13.7 Michael Carrigg, Inc. is a disk manufacturer in need of an aggregate plan for July through December. The company has gathered the following data: Holding cost Subcontracting Regular-time labor Overtime labor Hiring cost Layoff cost Costs $8/disk/month $80/disk $12/hour $18/hour for hours above 8 hours/worker/day $40/worker $80/worker Demand* July 400 Aug. 500 Sept. 550 Oct. 700 Nov. 800 Dec. 700 Other Data *No costs are incurred for unmet demand. Current workforce (June) Labor-hours/disk 8 people 4 hours Workdays/month Ending inventory Beginning inventory 20 days 150 disks** 0 disks **Note that there is no holding cost for June. What will each of the two following strategies cost?