Certified Maintenance & Reliability Professional (CMRP) Practice Exam

If a process operates at the Fifth Sigma level, what is the accepted percentage of defective parts?

1. 99.873%

2. 99.993%

3. 99.912%

4. 99.950%

The correct answer is: 99.993%

Operating at the Fifth Sigma level indicates a very high standard of quality, where the process is capable of producing a vast majority of defect-free products. Specifically, a process at the Fifth Sigma level limits the percentage of defective parts to 0.00057%. When converted to a percentage of accepted products versus defectives, this translates to an accepted percentage of 99.993%. The importance of the Sigma level is that it quantifies how often defects are likely to occur in a process. Each increase in Sigma level corresponds to a significant reduction in defect rates, reflecting enhanced process capabilities. The high Sigma levels like the Fifth Sigma are associated with near perfection in manufacturing or service delivery. In this context, the other percentage figures do not correspond to the Fifth Sigma level's acceptance rate of defects, as they indicate higher percentages of defectiveness, which would fall under lower Sigma levels. Thus, the accepted percentage of defective parts at the Fifth Sigma level being 0.007% confirms that 99.993% of the parts produced are non-defective, which aligns perfectly with the standard established for such a high-quality process.