Lean Six Sigma Black Belt Practice Exam — All Questions
4 questions
Control & SPC
On a control chart, a single point beyond the upper control limit indicates:
- a.That DPMO is zero
- b.A special (assignable) cause to investigate✓
- c.That the spec limits are wrong
- d.Common-cause variation
A point beyond the control limits signals special-cause variation to investigate.
Control & SPC
Control limits on a control chart are:
- a.Set by the customer
- b.Always ±1 sigma
- c.The same as the customer specification limits
- d.Calculated from the process data (typically ±3 sigma)✓
Control limits are derived from process variation (commonly ±3 sigma), distinct from spec limits.
Control & SPC
The main purpose of a control plan in the Control phase is to:
- a.Document how to monitor and sustain the improved process✓
- b.Run a DOE
- c.Define the project charter
- d.Compute Cp
A control plan documents monitoring and response to sustain the gains.
Control & SPC
Statistical Process Control (SPC) primarily helps distinguish:
- a.Common-cause from special-cause variation✓
- b.Costs from benefits
- c.Inputs from outputs
- d.Suppliers from customers
SPC separates normal common-cause variation from special-cause variation.