Up, Up, and Away is a producer of kites and windsocks. Relevant data on a bottleneck operation in the shop for the upcoming fiscal year are given in the following table:
ITEM KITES WINDSOCKS
Demand forecast 30,000 units/year 12,000 units/year
Lot size 20 units 70 units
Standard processing time 0.3 hour/unit 1.0 hour/unit
Standard setup time 3.0 hours/lot 4.0 hours/lot
The shop works two shifts per day, eight hours per shift, 200 days per year. There currently are four machines, and a 25% capacity cushion is desired. How many machines should be purchased to meet the upcoming year's demand without resorting to any short-term capacity solutions.