Lean Six Sigma Green Belt Practice Exam — All Questions

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

• a.2,500
• b.5,000✓
• c.40,000
• d.250

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.

Defects Per Unit (DPU) is calculated as:

• a.Total number of defects divided by total number of units✓
• b.Total number of defects times 1,000,000
• c.Number of units divided by number of defects
• d.Defects divided by the number of opportunities only

DPU = total defects / total units, a simple ratio of how many defects occur per unit produced. Multiplying by a million or dividing by opportunities describes DPMO or DPO, not DPU.

Using the common long-term sigma table (with the 1.5-sigma shift), a process operating at approximately 66,807 DPMO corresponds to what sigma level?

• a.6 sigma
• b.4 sigma
• c.3 sigma✓
• d.2 sigma

On the standard shifted sigma table, roughly 66,807 DPMO equals about a 3-sigma process (about 93.3% yield). Six sigma is about 3.4 DPMO and four sigma is about 6,210 DPMO.

Which type of data is 'the number of scratches found on each painted panel'?

• a.Continuous (variable) data
• b.Nominal data with no order
• c.A specification limit
• d.Discrete (attribute/count) data✓

Counts of defects are discrete attribute data because they take whole-number values. Continuous data (like length or weight) can take any value on a scale, and a count is not a specification limit.

In a Measurement System Analysis (Gage R&R), 'reproducibility' refers to the variation caused by:

• a.The same appraiser measuring the same part repeatedly
• b.Different appraisers measuring the same part with the same gage✓
• c.The natural variation of the manufacturing process
• d.The width of the specification tolerance

Reproducibility is the appraiser-to-appraiser (between-operator) variation. The same appraiser repeating a measurement is repeatability, and neither describes process variation or the tolerance itself.