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 0400 19 31 36 Click here for the Excel Data File Preventive Maintenance Cost 240 140 490 Probability Ratio Standard Deviation 2 3 6 Breakdown Cost 2 140 3 440 4 600 Interval days