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Determine the optimum preventive maintenance frequency for each of the pieces of equipment if breakdown time is normally distributed: (Round "Probability Ratio" to 4 decimal places, and all other answersto 2 decimal places. Negative values should be indicated by a minus sign.) Use Table. Equipment A201 B400 C850 Average Time (days) Standard between Breakdowns Deviation 20 2 30 3 40 4 Preventive Equipment Maintenance Cost A201 $300 B400 $200 C850 $530 Breakdown Cost $2,300 $3,500 $4,800 Probability Ratio Interval (days) Equipment A201 B400 C850