Up, up, and away is a producer of kites and wind socks. Relevant data on a bottleneck operation in the shop for the upcoming fiscal year are given in the following table: Item Kites Wind socks Demand forecast 30,000 units/year 12,000 units/year Lot size 20 units 70 units Standard processing time 0.3 hrs/unit 1.0 hr/unit Standard setup time 3.0 hrs/lot 4.0 hrs/lot The shop works 2 shifts per day, 8 hours per shift, 200 days per year. Currently, the company operates four machines, and desires a 25 percent capacity cushion. How many machines should be purchased to meet the upcoming year's demand without resorting to any short-term capacity solution?