Lean Six Sigma Green Belt Practice Exam

The main purpose of a control chart in the Control phase is to:

1. ARank problems from most to least frequent
2. BMap the suppliers and customers of a process
3. CProve a factor is statistically significant
4. DDistinguish common-cause variation from special-cause variation over timeCorrect

Why: Control charts plot data over time with control limits so teams can tell routine common-cause variation from special-cause signals that need action. Ranking, mapping, and significance testing are done with other tools.

A process inspects 500 units, each having 8 opportunities for a defect, and finds 20 defects. What is the DPMO?

1. A2,500
2. B40,000
3. C250
4. D5,000Correct

Why: DPMO = defects / (units x opportunities) x 1,000,000 = 20 / (500 x 8) x 1,000,000 = 20 / 4,000 x 1,000,000 = 5,000. Each answer that ignores the opportunity count or the scaling factor is incorrect.