Free Practice Test
Free Six Sigma Green Belt Practice Test
Take our free 10-question Six Sigma Green Belt exam practice test — covering the DMAIC framework, process capability, hypothesis testing, and control charts. No signup required. See your score instantly.
10 Free Six Sigma Green Belt Practice Questions
Q1. A new team member asks what Six Sigma primarily seeks to reduce in a business process. Which answer best fits the methodology?Show answer
✓ Correct Answer: Defects and process variation
Six Sigma is a disciplined methodology for reducing defects and process variation. Its goal is predictable performance that meets customer requirements. Headcount, demand, and supplier count may matter, but they are not the core purpose.
Q2. In a service project, a Green Belt writes what is wrong, where it occurs, and the business impact without suggesting causes. Which charter element is this?Show answer
✓ Correct Answer: Problem statement
A problem statement describes the issue, its magnitude, location, and impact. It should avoid assumed causes or solutions. Goal statements and reaction plans are developed for different purposes.
Q3. Case 201: In a service project, a CTQ tree starts with the need 'easy account setup.' Which branch is the best measurable CTQ?Show answer
✓ Correct Answer: Setup completed in less than 10 minutes
A CTQ must be specific and measurable. Setup time under 10 minutes converts a broad need into a measurable requirement. Vague statements cannot be reliably measured or improved.
Q4. A data set contains measured wait times of 8, 13, 15, 15, 16 minutes. What is the range of the observations?Show answer
✓ Correct Answer: 8
Range = maximum - minimum. The maximum is 16 and the minimum is 8, so range = 16 - 8 = 8 minutes. Range is a quick measure of spread.
Q5. Customer satisfaction is recorded on a 1 to 5 rating scale from very dissatisfied to very satisfied. What data type is this?Show answer
✓ Correct Answer: Ordinal data
Ordinal data have categories with a meaningful order. A 1 to 5 satisfaction scale is ordered, but the distance between ratings may not be equal. Nominal data have no inherent order.
Q6. A process improvement appears to reduce variation, but the gage contributes 35 percent of tolerance. What is the best conclusion?Show answer
✓ Correct Answer: Measurement error is too high to trust the improvement confidently
Gage R&R over 30 percent of tolerance is generally unacceptable. A noisy measurement system can mask or exaggerate process improvement. The team should improve measurement before relying heavily on the result.
Q7. In a service project, a team rejects the null hypothesis when it is actually true. What type of error has occurred?Show answer
✓ Correct Answer: Type I error
A Type I error is a false positive: rejecting a true null hypothesis. Its probability is alpha. A Type II error is failing to reject a false null hypothesis.
Q8. A hypothesis test comparing defect rates gives p = 0.012 with alpha = 0.05. What statistical decision should the team make?Show answer
✓ Correct Answer: Reject the null hypothesis
Compare the p-value with alpha. Here p = 0.012 is less than alpha = 0.05, so the team should reject the null hypothesis. The decision addresses statistical evidence, not the size of business impact.
Q9. In a service project, a setup reduction team converts adjustments performed while the machine is stopped into preparation done before shutdown. What is this called?Show answer
✓ Correct Answer: Moving internal setup to external setup
SMED distinguishes internal setup, done while stopped, from external setup, done while running. Moving work external reduces downtime. The goal is faster, more reliable changeover.
Q10. A Control phase handoff gives the process owner SOPs, monitoring charts, and escalation criteria. Why is this important?Show answer
✓ Correct Answer: It transfers ownership of the improved process
Control requires the improved process to be owned by operations. SOPs, charts, and escalation criteria help the owner maintain gains. Without handoff, improvements often decay.
What Does the Six Sigma Green Belt Exam Cover?
The Six Sigma Green Belt exam covers the full DMAIC methodology — Define, Measure, Analyze, Improve, and Control — plus statistics such as descriptive statistics, process capability, hypothesis testing, and control charts. The exact format depends on the certifying body. The ASQ Certified Six Sigma Green Belt (CSSGB) exam has 110 questions (about 100 scored) over roughly 4.5 hours, is open-book, requires about 550 of 750 points to pass, and requires documented work experience. The IASSC Certified Lean Six Sigma Green Belt (ICGB) exam is 100 questions, closed-book, 3 hours, with a 70 percent (385 of 500) passing score and no prerequisites. Both reward candidates who can apply the right tool in the right DMAIC phase.
How Hard Is the Six Sigma Green Belt Exam?
The Six Sigma Green Belt certification exam is moderately difficult, and the challenge depends on which body you test with. The ASQ CSSGB exam requires understanding the full DMAIC methodology plus statistics — descriptive statistics, process capability, hypothesis testing, and control charts — which trips up candidates weak on math. The IASSC ICGB is closed-book and purely exam-based. Both reward candidates who can apply the right tool in the right DMAIC phase rather than just recall definitions.
How to Study for the Six Sigma Green Belt Exam
- 1.Learn the DMAIC framework cold — Define, Measure, Analyze, Improve, and Control — and which tools belong in each phase.
- 2.Match tools to phases: SIPOC and the project charter in Define, process capability and MSA in Measure, and hypothesis tests and regression in Analyze.
- 3.Practice the statistics by hand: process capability (Cp and Cpk), control chart selection and interpretation, and hypothesis testing.
- 4.If your exam is open-book (ASQ), build a tabbed reference you can navigate fast.
- 5.If your exam is closed-book (IASSC), drill practice questions until your recall is automatic.
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