Lean Six Sigma Green Belt Practice Exam — All Questions

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

• a.Distinguish common-cause variation from special-cause variation over time✓
• b.Rank problems from most to least frequent
• c.Map the suppliers and customers of a process
• d.Prove a factor is statistically significant

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 has USL = 110, LSL = 90, mean = 100, and standard deviation = 2.5. What is the Cp (process capability)?

• a.1.00
• b.1.33✓
• c.0.67
• d.2.00

Cp = (USL - LSL) / (6 x sigma) = (110 - 90) / (6 x 2.5) = 20 / 15 = 1.33. A Cp of 1.33 corresponds to a four-sigma capable process when centered.

In Lean, which of the following is one of the classic categories of waste (muda)?

• a.Standardized work
• b.Value-added processing
• c.Overproduction✓
• d.Continuous flow

Overproduction, making more or sooner than needed, is one of the classic wastes and is often called the worst because it hides others. Standardized work, value-added processing, and continuous flow are goals, not wastes.

The 5S methodology (Sort, Set in order, Shine, Standardize, Sustain) is primarily aimed at:

• a.Designing a full factorial experiment
• b.Calculating rolled throughput yield
• c.Performing a measurement system analysis
• d.Organizing and maintaining an efficient, orderly workplace✓

5S creates and sustains a clean, organized, visual workplace that exposes abnormalities and supports flow. It is a workplace-organization method, not an experimental, yield, or measurement technique.

A control plan created at the end of a project is intended mainly to:

• a.Sustain the gains by specifying what to monitor, how, and the reaction plan if limits are exceeded✓
• b.Define the original problem statement
• c.Replace the need for any ongoing measurement
• d.Calculate the project's net present value

The control plan documents the key characteristics to monitor, the method and frequency, and the response if the process drifts, so improvements hold over time. It defines ongoing monitoring rather than eliminating it, and it is not a Define or finance tool.