Lean Six Sigma Black Belt Practice Exam — All Questions

In hypothesis testing, if the p-value is 0.03 and alpha is 0.05, you should:

• a.Increase the sample to 1,000 first
• b.Do nothing; p-values are irrelevant
• c.Fail to reject the null hypothesis
• d.Reject the null hypothesis✓

Because p (0.03) < alpha (0.05), you reject the null hypothesis.

A Type I error occurs when you:

• a.Increase the sample size
• b.Accept a true null hypothesis
• c.Compute DPMO incorrectly
• d.Reject a true null hypothesis (a false positive)✓

A Type I (alpha) error is rejecting a null hypothesis that is actually true.

A correlation coefficient (r) of -0.9 indicates:

• a.A weak positive relationship
• b.A guaranteed causal link
• c.A strong negative linear relationship✓
• d.No relationship

r = -0.9 indicates a strong negative linear correlation (correlation is not causation).

Which tool helps prioritize the 'vital few' causes contributing most to a problem?

• a.SIPOC
• b.Control chart
• c.Gage R&R
• d.Pareto chart✓

A Pareto chart highlights the vital few causes (the 80/20 principle).