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 answers to 2 decimal places. Negative values should be indicated by a minus sign.) Use Table. Equipment A201 B400 C850 Equipment A201 B400 C850 Equipment Average Time (days) between Breakdowns A201 B400 C850 19 29 44 Click here for the Excel Data File Preventive Maintenance Cost $320 $220 $570 Probability Ratio Standard Deviation 224 Breakdown Cost $2,220 $3,520 $4,800 Z Interval (days)

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 answers to 2 decimal places. Negative values should be indicated by a minus sign.) Use Table. Click here for the Excel Data File