Problem 14S-3 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 Average Time (days) between Breakdowns 20 Equipment A201 B400 C850 Standard Deviation 2 3 4 30 40 Equipment A201 B400 C850 Preventive Maintenance Cost $300 $200 $530 Breakdown Cost $2,300 $3,500 $4,800 Probability Ratio Interval (days) Equipment A201 B400 C850