Six Sigma Green Belt Practice Questions 2026: Free CSSGB Sample Problems

Why Practice Questions Are Essential for CSSGB Success

Studying Six Sigma theory is one thing. Applying that knowledge under timed exam conditions is something else entirely. The ASQ Certified Six Sigma Green Belt exam tests 110 multiple-choice questions across all six DMAIC domains, and candidates who rely solely on reading reference materials often struggle with the application-based format of the actual test. Practice questions bridge the gap between understanding a concept and correctly answering a question about it when the clock is ticking.

With pass rates sitting at 77% in 2024, the CSSGB is certainly achievable — but that still means roughly one in four test-takers walks away without a passing score. The candidates who pass consistently point to one habit that made the difference: regular, structured practice with realistic sample problems.

Below, you'll find free practice questions organized by each of the six exam domains, complete with detailed answer explanations. Use these alongside your complete CSSGB study guide to pinpoint weak areas and sharpen your exam readiness.

Understanding the CSSGB Exam Structure Before You Practice

Before diving into sample problems, it helps to understand exactly what you're preparing for. The ASQ CSSGB exam is a computer-based test (CBT) administered at Prometric centers or via remote proctoring. Of the 110 questions, only 100 are scored — the remaining 10 are unscored pretest items used by ASQ to evaluate future questions. You won't know which questions are unscored, so treat every question as if it counts.

The exam is open-book, meaning you can bring bound reference materials into the testing room. This is a significant advantage, but only if you've organized your materials properly. For strategies on maximizing your reference materials, read our guide on open-book strategies and reference material preparation.

Domain	Weight	Approx. Scored Questions	Key Topics
Overview: Six Sigma and the Organization	11%	~11	Six Sigma history, lean, organizational value
Define Phase	20%	~20	Project charters, VOC, SIPOC, stakeholders
Measure Phase	20%	~20	Data collection, MSA, process capability, SPC basics
Analyze Phase	18%	~18	Hypothesis testing, regression, root cause analysis
Improve Phase	16%	~16	DOE, lean tools, kaizen, solution selection
Control Phase	15%	~15	SPC charts, control plans, sustaining gains

Domain 1: Overview — Six Sigma and the Organization (11%)

Question 1

A manufacturing company is considering deploying Six Sigma. The executive sponsor asks what sigma level corresponds to 3.4 defects per million opportunities. What is the correct answer?

1. 4 sigma
2. 5 sigma
3. 6 sigma
4. 4.5 sigma

Question 2

Which of the following best describes the role of a Green Belt within a Six Sigma organization?

1. A full-time project leader who manages large-scale Six Sigma projects across departments
2. A part-time practitioner who applies Six Sigma tools to projects within their functional area while maintaining regular job duties
3. A senior executive who sponsors and funds Six Sigma initiatives
4. A statistical expert who provides advanced analytical support to Black Belt projects

Question 3

An organization has identified waste in the form of excess inventory, unnecessary motion, and overproduction. These wastes are most closely associated with which methodology?

1. Design for Six Sigma (DFSS)
2. Lean enterprise
3. Total Quality Management (TQM)
4. Theory of Constraints (TOC)

Domain 2: Define Phase Questions (20%)

The Define phase is one of the two highest-weighted domains. For an in-depth breakdown of this critical phase, see our CSSGB Define Phase study guide.

Question 4

A Green Belt is developing a project charter. Which of the following elements is MOST critical for establishing the project's boundaries?

1. Business case
2. Problem statement
3. Project scope
4. Goal statement

Question 5

A SIPOC diagram is used during the Define phase to:

1. Identify root causes of process variation
2. Provide a high-level view of the process including suppliers, inputs, process steps, outputs, and customers
3. Prioritize potential solutions based on cost and benefit
4. Establish statistical control limits for key process outputs

Question 6

The Voice of the Customer (VOC) has been translated into Critical to Quality (CTQ) requirements. A customer states: "I want my order delivered quickly." Which of the following is the best CTQ translation?

1. Orders should be delivered as fast as possible
2. Delivery time from order placement to receipt shall not exceed 48 hours
3. Customers will be satisfied with delivery speed
4. The company will improve its delivery process

Domain 3: Measure Phase Questions (20%)

The Measure phase shares the top weighting with Define, and it's where many candidates encounter their first statistical challenges. For a deeper dive into the statistical tools tested, review our guide on statistical tools you must know for the Measure and Analyze phases.

Question 7

A quality engineer collects 25 subgroups of 5 samples each from a stable process. The overall mean is 50.0 and the average range is 4.6. Using A₂ = 0.577 for n=5, what are the upper and lower control limits for the X-bar chart?

1. UCL = 52.65, LCL = 47.35
2. UCL = 54.60, LCL = 45.40
3. UCL = 53.27, LCL = 46.73
4. UCL = 51.33, LCL = 48.67

Question 8

A measurement system analysis (Gage R&R) study shows that the measurement system accounts for 35% of the total observed variation. What should the Green Belt conclude?

1. The measurement system is acceptable and the team should proceed to analysis
2. The measurement system is marginally acceptable and may require improvement
3. The measurement system is unacceptable and must be improved before reliable data can be collected
4. The measurement system variation is irrelevant if the process is in control

Question 9

A process has a Cpk of 1.0 and a Cp of 1.5. Which of the following statements is correct?

1. The process is centered and capable
2. The process is capable but not centered within the specification limits
3. The process is neither capable nor centered
4. The specification limits need to be widened

Domain 4: Analyze Phase Questions (18%)

Question 10

A Green Belt performs a hypothesis test and obtains a p-value of 0.03 with a significance level (alpha) of 0.05. What is the correct conclusion?

1. Fail to reject the null hypothesis; the result is not statistically significant
2. Reject the null hypothesis; there is sufficient evidence of a statistically significant difference
3. Accept the null hypothesis; the process means are equal
4. The test is inconclusive and more data is needed

Question 11

A fishbone (Ishikawa) diagram is used during root cause analysis. Which of the following is NOT one of the traditional 6M categories?

1. Manpower
2. Measurement
3. Management
4. Mother Nature (Environment)

Question 12

A scatter diagram shows data points that cluster tightly around a line sloping from the lower-left to the upper-right of the chart. This pattern indicates:

1. A strong negative correlation between the two variables
2. No correlation between the two variables
3. A strong positive correlation between the two variables
4. A cause-and-effect relationship between the two variables

Domain 5: Improve Phase Questions (16%)

The Improve phase focuses on generating, selecting, and implementing solutions. For comprehensive coverage of DOE, lean tools, and kaizen concepts tested on the exam, see our Improve Phase study guide.

Question 13

A Green Belt designs a 2³ full factorial experiment. How many experimental runs are required (without replication)?

1. 6
2. 8
3. 9
4. 12

Question 14

During a kaizen event, the team identifies that operators walk an average of 200 feet between workstations to retrieve parts. Which lean tool is MOST appropriate for addressing this waste?

1. Poka-yoke
2. 5S workplace organization
3. Spaghetti diagram and cell layout redesign
4. Value stream mapping

Question 15

When evaluating potential solutions, a team uses a criteria-based matrix that scores each solution on factors such as cost, time to implement, and effectiveness. This tool is called a:

1. Pareto chart
2. Failure mode and effects analysis (FMEA)
3. Pugh matrix (decision matrix)
4. Quality function deployment (QFD)

Domain 6: Control Phase Questions (15%)

Question 16

A Green Belt is selecting an appropriate control chart for monitoring the number of defects per unit on circuit boards. Which chart is most appropriate?

1. p-chart
2. np-chart
3. c-chart
4. u-chart

Question 17

Which of the following is a primary purpose of a control plan?

1. To identify the root cause of process variation
2. To document the system for maintaining process improvements, including monitoring methods, reaction plans, and responsibilities
3. To calculate the cost savings from a completed Six Sigma project
4. To define the project scope and objectives

Question 18

On an X-bar and R chart, seven consecutive points fall above the center line. This pattern indicates:

1. The process is in statistical control
2. Normal random variation
3. A special cause of variation is likely present (run rule violation)
4. The control limits need to be recalculated

For a thorough review of SPC charts, control plans, and all Control phase concepts, check out our CSSGB Control Phase study guide.

Detailed Answer Explanations

Questions 1–3: Overview Domain

Question 1 — Answer: C (6 sigma). The benchmark performance level of Six Sigma is 3.4 defects per million opportunities (DPMO). This accounts for the typical 1.5 sigma long-term shift. While 4.5 sigma (without shift) also yields approximately 3.4 DPMO, the standard answer to "what sigma level equals 3.4 DPMO" is 6 sigma, which is the foundational definition of the methodology.

Question 2 — Answer: B. Green Belts are part-time practitioners who work on Six Sigma projects within their functional areas while continuing their regular responsibilities. Black Belts (not Green Belts) are typically full-time project leaders. Champions and sponsors are senior executives, and Master Black Belts serve as statistical experts and mentors.

Question 3 — Answer: B (Lean enterprise). The eight wastes (often remembered by the acronym DOWNTIME or TIM WOODS) — including inventory, motion, and overproduction — are core lean concepts. While Six Sigma focuses on reducing variation, lean focuses on eliminating waste and improving flow.

Questions 4–6: Define Phase

Question 4 — Answer: C (Project scope). While all elements listed are part of a project charter, the project scope specifically defines what is included and excluded from the project — establishing its boundaries. The business case justifies the project, the problem statement describes the issue, and the goal statement defines the target outcome.

Question 5 — Answer: B. SIPOC stands for Suppliers, Inputs, Process, Outputs, and Customers. It provides a high-level process overview and is typically one of the first tools used in the Define phase. It does not identify root causes (that's Analyze), prioritize solutions (that's Improve), or establish control limits (that's Control).

Question 6 — Answer: B. A valid CTQ must be specific, measurable, and actionable. "Delivery time shall not exceed 48 hours" meets all three criteria. The other options are vague, unmeasurable, or describe process improvements rather than measurable customer requirements.

Questions 7–9: Measure Phase

Question 7 — Answer: A (UCL = 52.65, LCL = 47.35). For an X-bar chart: UCL = X-double-bar + A₂ × R-bar = 50.0 + (0.577 × 4.6) = 50.0 + 2.6542 = 52.65. LCL = 50.0 − 2.6542 = 47.35. This is a straightforward control limit calculation that regularly appears on the exam.

Question 8 — Answer: C (Unacceptable). AIAG guidelines state that a Gage R&R below 10% is acceptable, between 10% and 30% is marginally acceptable, and above 30% is unacceptable. At 35%, the measurement system contributes too much variation for reliable data collection and analysis.

Question 9 — Answer: B. When Cp exceeds Cpk, it indicates the process has adequate spread (capability) but is not centered between the specification limits. Cp measures potential capability (spread only), while Cpk accounts for both spread and centering. Equal values would indicate a centered process.

Questions 10–12: Analyze Phase

Question 10 — Answer: B. When the p-value (0.03) is less than alpha (0.05), we reject the null hypothesis. This means there is sufficient statistical evidence to conclude a significant difference exists. Note: we never "accept" the null hypothesis — we either reject it or fail to reject it.

Question 11 — Answer: C (Management). The traditional 6Ms are: Manpower (People), Machine, Method, Material, Measurement, and Mother Nature (Environment). "Management" is not one of the standard categories, though some organizations add it as a seventh M in practice.

Question 12 — Answer: C (Strong positive correlation). A lower-left to upper-right pattern shows a positive correlation — as one variable increases, the other tends to increase. Answer D is a common trap: correlation does not imply causation. A scatter diagram shows correlation, not cause-and-effect relationships.

Questions 13–15: Improve Phase

Question 13 — Answer: B (8 runs). A full factorial design with k factors at 2 levels requires 2ᵏ runs. For 2³: 2 × 2 × 2 = 8 experimental runs. This is a fundamental DOE calculation.

Question 14 — Answer: C. A spaghetti diagram visually maps the physical movement of operators or materials, making excessive motion waste clearly visible. The resulting cell layout redesign minimizes travel distance. While 5S could help, the spaghetti diagram with layout redesign directly targets the motion waste described.

Question 15 — Answer: C (Pugh matrix). The Pugh matrix (also called a decision matrix or criteria-based matrix) evaluates and scores potential solutions against weighted criteria. FMEA evaluates failure modes, not solutions. Pareto charts prioritize by frequency, and QFD translates customer needs into design requirements.

Questions 16–18: Control Phase

Question 16 — Answer: D (u-chart). The u-chart monitors defects per unit when the sample size varies. The c-chart also tracks defects, but requires a constant sample size. The p-chart and np-chart track defective units (proportion and count, respectively), not defects per unit. Since circuit boards can have multiple defects each, defects per unit is the appropriate metric.

Question 17 — Answer: B. A control plan documents how process improvements will be sustained after the project ends. It specifies what to monitor, how to measure it, who is responsible, and what corrective actions to take when the process deviates. It is a key deliverable of the Control phase.

Question 18 — Answer: C. The Western Electric rules (Nelson rules) state that seven or more consecutive points on the same side of the center line indicate a non-random pattern — a likely special cause of variation. This is a run rule violation that requires investigation, not just a recalculation of limits.

How to Use Practice Questions Effectively

Simply answering practice questions won't automatically improve your score. How you practice matters as much as how much you practice. Follow these strategies to get the maximum benefit from every sample problem you work through.

Common Exam Traps and How to Avoid Them

ASQ exam writers are skilled at crafting distractors that punish surface-level understanding. Here are the most common traps candidates encounter and how to avoid them.

"Best" and "Most" qualifiers: When a question asks for the "best" or "most appropriate" answer, multiple options may seem partially correct. Read all four choices before selecting. The correct answer is the one that most directly and completely addresses what the question asks.

Mixing up defects vs. defectives: A defect is a single instance of nonconformance. A defective is an entire unit that contains one or more defects. This distinction determines which control chart to use (p/np for defectives, c/u for defects) and frequently appears on the exam.

Forgetting the open-book advantage: Some candidates try to memorize every formula and table value. This leads to stress and errors. Instead, know where to find critical information in your reference materials and focus your memorization on concepts, definitions, and decision frameworks. Read more about this approach in our 8-week CSSGB study plan.

Overthinking straightforward questions: Not every question is a trick question. If a question seems simple, it might just be one of the easier items in the test bank. Answer it confidently and move on. Second-guessing wastes precious time.

For a comprehensive look at what makes the exam challenging and how to set your expectations, read our analysis on CSSGB exam difficulty and historical pass rates. And when you're ready to understand the full return on your investment — from exam fees to salary impact — explore our guides on certification costs and salary impact of CSSGB certification.

Frequently Asked Questions