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EXIN LSSA Green Belt Practical study materials
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EXIN LSSA Green Belt Practical practice questions

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Question 1Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is mapping a process and needs to distinguish value-adding from non-value-adding steps. Which activity qualifies as value-adding in Lean thinking?

  1. A step that moves material between two warehouses
  2. A step that changes the form, fit, or function of the product the customer pays for Correct answer.
  3. A step that is required by the company's internal accounting policy
  4. A step that reworks a defect found during final inspection

Explanation

Lean defines a value-adding activity as one the customer would willingly pay for, which means it physically or informationally transforms the product toward what the customer wants, done right the first time. Internal reporting requirements, rework, and transport add cost or time but do not transform the offering for the customer.

Question 2Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

During a value stream mapping session, a team records a process step with a cycle time of 45 seconds, a changeover time of 30 minutes, and 98% uptime. Which Lean metric does the team need to calculate to reflect the availability and quality of that step in the future-state design?

  1. Little's Law inventory
  2. Overall equipment effectiveness Correct answer.
  3. Rolled throughput yield
  4. Takt time

Explanation

Overall equipment effectiveness combines availability, performance, and quality into one number, so it captures the effect of uptime losses and changeover on how much good output a step can deliver. Takt time is set by customer demand, rolled throughput yield measures cumulative first-pass yield across steps, and Little's Law relates inventory, flow time, and throughput.

Question 3Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A team is building a cause-and-effect diagram for excessive scrap on a welding line. Which action best follows the Lean Six Sigma approach to brainstorming causes?

  1. Rank causes by how easy they are to fix and address those first
  2. List candidate causes in the 5M1E categories and then verify the strongest ones with data Correct answer.
  3. Implement countermeasures for every listed cause at once
  4. Select the cause that the most senior operator believes is responsible

Explanation

Cause-and-effect analysis is a divergent-then-convergent tool: the team generates candidate causes across categories such as man, machine, material, method, measurement, and environment, then uses data to confirm which causes actually matter. Selecting a cause by opinion, acting on all causes simultaneously, or prioritizing by ease of fixing all skip the verification step that makes the analysis reliable.

Question 4Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt collects 30 measurements of cycle time and wants a quick graphical check of the distribution's shape, center, and spread before running capability analysis. Which tool is most appropriate?

  1. A scatter plot of cycle time against operator tenure
  2. A Pareto chart of defect categories
  3. A histogram of the 30 cycle times Correct answer.
  4. A p-chart of the 30 cycle times

Explanation

A histogram bins continuous data and displays shape, center, and spread, which is exactly what is needed before choosing a capability index. The other charts answer different questions: attribute control, defect prioritization, or the relationship between two variables.

Question 5Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A process has specification limits of 10 and 20 and an estimated standard deviation of 1.0. The process mean is 17. Which statement about capability is correct?

  1. Cp and Cpk are both about 1.00, so the process is centered
  2. Cp is about 1.67 but Cpk is about 1.00, so the process is off-center Correct answer.
  3. Cp is about 1.00 but Cpk is about 1.67, so the process is centered
  4. Cp and Cpk are both about 1.67, so the process is capable and centered

Explanation

Cp equals specification width divided by six sigma, or 10 divided by 6, which is about 1.67. Cpk takes the smaller distance from the mean to a specification limit divided by three sigma; here that is 3 divided by 3, or 1.00, showing the mean sits off-center toward the upper limit.

Question 6Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is planning a measurement systems analysis for a continuous gauge. Which study design is appropriate for assessing repeatability and reproducibility?

  1. Ten parts measured once each by one appraiser
  2. Ten parts measured by three appraisers in a randomized order, two or three trials each Correct answer.
  3. One part measured ten times by one appraiser
  4. Three parts measured by three appraisers once each

Explanation

A gauge R&R study needs multiple parts spanning the process variation, multiple appraisers, and repeated trials so that within-appraiser variation (repeatability) and between-appraiser variation (reproducibility) can be separated. Single-appraiser or single-trial designs cannot isolate both components.

Question 7Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A team runs a two-sample t-test and obtains a p-value of 0.03 with alpha set at 0.05. What is the correct interpretation?

  1. The probability the null hypothesis is true equals 3%
  2. There is a 97% chance the alternative hypothesis is true
  3. There is statistically significant evidence of a difference in means at the 5% level Correct answer.
  4. The difference in means is large enough to be practically important

Explanation

A p-value below the chosen alpha leads to rejecting the null hypothesis, so the team concludes a statistically significant difference exists at the 5% significance level. The p-value is not the probability that a hypothesis is true, and statistical significance does not by itself establish practical importance.

Question 8Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt wants to compare the mean strength of a product across four different suppliers. Which test is most appropriate when the data are continuous and roughly normal?

  1. One-way analysis of variance Correct answer.
  2. Paired t-test
  3. Sign test
  4. Chi-square test of independence

Explanation

One-way ANOVA compares the means of three or more groups on a continuous response while controlling the overall error rate. Chi-square handles categorical associations, a paired t-test handles two related samples, and the sign test is a nonparametric procedure for paired or single-sample medians.

Question 9Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A process is monitored with a control chart. Six consecutive points fall on one side of the centerline. What should the Green Belt conclude?

  1. A non-random pattern signals a likely shift that should be investigated Correct answer.
  2. The control limits are too wide and should be recalculated immediately
  3. The process is in control because no point exceeded a control limit
  4. The data must be normally distributed for the pattern to matter

Explanation

Run rules detect small shifts that individual points outside the limits may miss; six points in a row on one side of the centerline is a recognized signal of a process shift. Control-limit violations are only one type of signal, and the run rule does not depend on the data being normal.

Question 10Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A team wants to reduce setup time on a press before reducing batch size. Which Lean technique directly targets changeover reduction?

  1. Kanban replenishment
  2. Single-minute exchange of die Correct answer.
  3. Poka-yoke mistake-proofing
  4. Heijunka leveling

Explanation

Single-minute exchange of die, or SMED, systematically separates internal from external setup tasks and converts internal tasks to external ones to shrink changeover time. Kanban controls replenishment, heijunka levels production volume and mix, and poka-yoke prevents errors.

Question 11Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt calculates takt time as 480 minutes of available time divided by 240 units of customer demand per shift. What is the takt time?

  1. 2.0 minutes per unit Correct answer.
  2. 0.5 minutes per unit
  3. 480 minutes per unit
  4. 240 minutes per unit

Explanation

Takt time equals available production time divided by customer demand, so 480 divided by 240 gives 2.0 minutes per unit. This is the pace at which the process must complete one unit to meet demand within the available time.

Question 12Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A team finds that 80% of customer complaints come from three of twenty defect categories. Which tool best communicates this prioritization to management?

  1. A control chart
  2. A fishbone diagram
  3. A run chart
  4. A Pareto chart Correct answer.

Explanation

The Pareto chart ranks categories in descending frequency and shows cumulative contribution, making the vital few visible. This directly supports the 80/20 prioritization the team observed.

Question 13Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt must decide whether to use a Kanban pull system. Which condition most supports that decision?

  1. The process has large batch changeovers and no standard work
  2. The product is custom-engineered one unit at a time
  3. Demand is highly erratic and lead times vary widely
  4. Demand is relatively stable and replenishment lead times are predictable Correct answer.

Explanation

Pull systems rely on predictable replenishment so that a consumed kanban can be refilled within its lead time; stable demand and reliable lead times make this feasible. Erratic demand, unstandardized large-batch processes, and one-off custom products undermine simple kanban sizing.

Question 14Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is defining the scope of a DMAIC project. Which element belongs in a project charter?

  1. The full statistical analysis plan with all test outputs
  2. The problem statement, goal, scope boundaries, and team roles Correct answer.
  3. The final control plan and response strategy
  4. The detailed future-state value stream map

Explanation

A charter establishes the business case, problem and goal statements, scope, milestones, and team roles at project launch. The analysis plan, control plan, and future-state map are developed later in the Measure, Improve, and Control phases.

Question 15Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A team is calculating the cost of poor quality for a project. Which item is an internal failure cost?

  1. Inspection of incoming raw material
  2. Scrap generated before the product reaches the customer Correct answer.
  3. Customer complaint handling after delivery
  4. Warranty replacement of a failed unit in the field

Explanation

Internal failure costs arise from defects detected before shipment, such as scrap, rework, and re-inspection. Warranty and complaint handling are external failure costs, while incoming inspection is an appraisal cost.

Question 16Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt runs a regression of cycle time on two predictors and finds variance inflation factors above 10. What does this indicate?

  1. Non-normality of the response, which invalidates the model
  2. Autocorrelation of residuals, which inflates the R-squared
  3. Heteroscedasticity of the residuals, which biases the intercept
  4. Multicollinearity among the predictors, which destabilizes coefficient estimates Correct answer.

Explanation

A variance inflation factor above roughly 10 signals that predictors are highly correlated with each other, so individual coefficient estimates become unstable and hard to interpret. It does not diagnose residual variance patterns, response normality, or serial correlation.

Question 17Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A team wants to screen five factors for their effect on yield with a limited number of runs. Which design is most efficient for this purpose?

  1. A full factorial design with all interactions
  2. A one-factor-at-a-time experiment
  3. A fractional factorial design Correct answer.
  4. A completely randomized design with no factors

Explanation

A fractional factorial uses a carefully chosen subset of runs to estimate main effects and key interactions with far fewer trials, which suits screening many factors. Full factorials become impractical as factors grow, one-factor-at-a-time misses interactions, and a design with no factors tests nothing.

Question 18Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A process is in statistical control but its capability index Cpk is 0.8. What is the correct conclusion?

  1. The specification limits must be wrong
  2. The process is stable but not capable of meeting specifications consistently Correct answer.
  3. The process is unstable and capability cannot be assessed
  4. The process is capable because it is in control

Explanation

Statistical control means only common-cause variation is present; capability compares that variation to the specification width. A Cpk of 0.8 indicates the process spread relative to specifications is too large and off-center, so it will produce defects even while stable.

Question 19Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is applying the 5S methodology on a shop floor. Which activity corresponds to the 'Seiso' step?

  1. Sustaining the gains through audits and discipline
  2. Cleaning equipment and the workplace and identifying sources of dirt Correct answer.
  3. Sorting and removing unneeded items
  4. Establishing visual standards and schedules

Explanation

Seiso means cleaning and inspecting, which reveals abnormal conditions and sources of contamination. Sorting is Seiri, standardizing is Seiketsu, and sustaining is Shitsuke.

Question 20Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A team wants to verify that a new fixture reduced variation, not just the mean, in a critical dimension. Which analysis directly addresses this question?

  1. A Pareto chart of defect types
  2. An F-test comparing variances of the before and after samples Correct answer.
  3. A one-sample t-test of the after-process mean
  4. A chi-square goodness-of-fit test

Explanation

Comparing variances with an F-test (or an equivalent variance-ratio procedure) tests whether the spread changed, which is separate from a shift in the mean. The other options address means, category frequencies, or defect prioritization.

Question 21Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is selecting between two improvement solutions. Which approach best supports a defensible decision?

  1. Pilot both simultaneously without predefined criteria
  2. Choose the option with the lowest upfront cost
  3. Adopt whichever solution the sponsor prefers
  4. Score each option against weighted criteria such as impact, cost, and risk Correct answer.

Explanation

A weighted decision matrix makes criteria and their relative importance explicit, allowing the team to compare options transparently. Choosing by cost alone, by sponsor preference, or without criteria introduces bias and ignores trade-offs.

Question 22Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A control plan for a critical process parameter should include which set of elements?

  1. Only the target value and the operator's name
  2. Only the historical mean and standard deviation
  3. What is monitored, the method and frequency, the specification or limits, and the reaction plan Correct answer.
  4. Only the audit schedule and training records

Explanation

A control plan documents the characteristic, monitoring method, sample size and frequency, control limits or specification, and the response when out-of-control conditions occur. Omitting any of these leaves the process without a defined reaction to problems.

Question 23Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt observes that inventory between two workstations is high and flow time is long. According to Little's Law, which action reduces flow time while holding throughput constant?

  1. Reduce the work-in-process inventory between the stations Correct answer.
  2. Increase the number of units released per hour
  3. Add a queue buffer before the downstream station
  4. Increase the batch size at the upstream station

Explanation

Little's Law states that flow time equals work-in-process divided by throughput, so at constant throughput, lowering WIP directly shortens flow time. Increasing batch size, adding buffers, or raising release rates tends to raise WIP and lengthen flow time.

Question 24Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A team is performing a failure mode and effects analysis. Which combination determines the risk priority number for a failure mode?

  1. Severity multiplied by occurrence multiplied by detection Correct answer.
  2. Occurrence divided by detection
  3. Severity multiplied by detection only
  4. Severity added to occurrence added to detection

Explanation

The risk priority number is the product of severity, occurrence, and detection ratings, each scored on a defined scale. Multiplicative combination reflects that risk grows with all three dimensions, whereas addition or omission of a factor distorts prioritization.

Question 25Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt analyzes a process where 12% of units are defective and wants to monitor the proportion defective over time with varying sample sizes. Which control chart is appropriate?

  1. An X-bar and R chart
  2. A c-chart
  3. An individuals and moving range chart
  4. A p-chart with variable control limits Correct answer.

Explanation

A p-chart tracks the proportion defective for attribute data, and when subgroup sizes vary, the control limits are recalculated for each subgroup. X-bar and R charts and individuals charts require continuous data, and a c-chart counts defects per unit rather than defective units.

Question 26Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is facilitating a value stream mapping session and wants to record how long a unit waits between two processes versus how long it is actually worked on. Which pair of measures should be captured for each process box?

  1. Rolled throughput yield and first pass yield
  2. Takt time and pitch
  3. OEE and MTBF
  4. Lead time and cycle time Correct answer.

Explanation

Value stream maps capture both the waiting time (lead time, or inventory divided by daily demand) and the value-adding processing time (cycle time) for each step, so that the ratio between them reveals hidden delay. Yield and availability metrics describe quality and equipment, not the flow of a unit through time.

Question 27Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

During a kaizen event, a team physically reorganizes the tool board so that each tool has a marked location and is returned immediately after use. Which 5S step does this activity primarily represent?

  1. Shitsuke, building self-discipline
  2. Seiton, arranging and designating locations Correct answer.
  3. Seiketsu, standardizing and sustaining
  4. Seiri, sorting out unneeded items

Explanation

Seiton (set in order) is the step where every needed item gets a defined, labeled location so it can be found and returned quickly. Sorting removes unneeded items, while standardization and discipline come later and focus on maintaining the gains.

Question 28Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is preparing a process map and needs to distinguish steps that add value from those that do not. Which test is the standard criterion for a step to be value-adding?

  1. The step appears on the routing sheet approved by engineering
  2. The step is required by the internal quality procedure
  3. The step uses a machine rather than manual labor
  4. The customer would pay for it and it is done right the first time Correct answer.

Explanation

A step adds value only if it changes the form, fit, or function of the product in a way the customer values and it is performed correctly the first time. Internal procedures, equipment type, and routing documentation may be necessary but do not by themselves make a step value-adding.

Question 29Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is building a Pareto chart of defect types and wants to decide which categories to combine. Which practice produces the most useful chart?

  1. Rank categories by the cost of the control measure used to address them
  2. List categories alphabetically so readers can locate each one
  3. Rank categories by frequency and group the smallest tail into an 'other' category Correct answer.
  4. Plot every category separately regardless of how few occurrences it has

Explanation

A Pareto chart orders categories by magnitude so the vital few stand out, and folding the long tail into a single 'other' bar keeps the chart readable without distorting the ranking. Alphabetical or cost-based ordering hides the relative contribution of each defect type.

Question 30Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is writing a problem statement for a DMAIC charter. Which statement is best constructed?

  1. Pricing errors occur because the team does not care enough
  2. Billing is a problem area that many people complain about
  3. From January to March, 8.2% of invoiced orders were reworked for pricing errors, against a target of 2.0% Correct answer.
  4. We must improve billing accuracy by implementing new software

Explanation

A good problem statement quantifies the gap, states the metric, the time frame, and the target, without prescribing a solution or a cause. The other choices are vague, solution-driven, or blame-oriented, none of which belongs in a charter problem statement.

Question 31Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is selecting a Lean tool to expose the sequence of steps and decision points a customer experiences when contacting a service center. Which tool fits best?

  1. Kanban board
  2. Spaghetti diagram
  3. X-bar and R chart
  4. Service blueprint Correct answer.

Explanation

A service blueprint maps the customer journey together with front-stage and back-stage activities, decision points, and supporting systems, which is exactly what a service process needs. A spaghetti diagram traces physical movement, a Kanban board controls work flow, and a control chart monitors a statistic over time.

Question 32Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A team is setting up a pull system between a machining cell and assembly. Which element is essential for the pull signal to function?

  1. A weekly forecast issued by the sales department
  2. A defined, limited amount of buffer inventory at the downstream point Correct answer.
  3. A buffer sized to cover the worst possible demand spike
  4. A dedicated expediter who walks material between areas

Explanation

Pull works when downstream consumption triggers replenishment of a controlled, limited buffer; the cap on inventory is what makes the signal meaningful. Forecasts push work, expediters substitute for flow, and oversized buffers hide problems instead of exposing them.

Question 33Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is reviewing a control chart and sees a single point beyond the upper control limit. What is the appropriate first response?

  1. Switch to a chart with wider limits such as an individual moving range chart
  2. Investigate the process for a special cause at that time and contain any affected output Correct answer.
  3. Conclude that the process is capable and take no action
  4. Recalculate the control limits so the point falls inside them

Explanation

A point outside a control limit is the classic signal of a special cause, so the team should look for what changed and protect the customer from suspect output. Recomputing limits or changing chart types to absorb the point would mask a real signal.

Question 34Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt needs to estimate the proportion of transactions containing an error when each transaction can have several independent error opportunities. Which metric is most appropriate?

  1. Overall equipment effectiveness
  2. Cycle time
  3. Defects per million opportunities Correct answer.
  4. Rolled throughput yield

Explanation

Defects per million opportunities normalizes defect counts by the number of chances for error, which is exactly what is needed when transactions vary in complexity. Rolled throughput yield measures the probability of passing all steps, cycle time measures duration, and OEE measures equipment effectiveness.

Question 35Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is stratifying defect data by shift, machine, and operator before running any statistical test. What is the main purpose of this stratification?

  1. To increase the sample size so that p-values become smaller
  2. To reveal whether the aggregate defect rate masks differences between subgroups Correct answer.
  3. To convert attribute data into continuous data
  4. To prove that the process is in statistical control

Explanation

Stratification separates a pooled dataset into meaningful subgroups so that patterns hidden by aggregation, such as one machine driving most defects, become visible. It does not change the underlying data type, guarantee control, or legitimately manufacture significance.

Question 36Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A team suspects that defect rate depends on which of three operators runs the process. The data are counts of defective and non-defective units per operator. Which analysis is appropriate?

  1. One-way ANOVA on the defect counts
  2. Simple linear regression of defect count on operator
  3. Paired t-test between operator 1 and operator 2
  4. Chi-square test of independence on the operator-by-defect contingency table Correct answer.

Explanation

Two categorical variables, operator and defect status, with counts in each cell call for a chi-square test of independence. ANOVA and t-tests require a continuous response, and regression on an unordered categorical predictor with counted outcomes is not the standard approach.

Question 37Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt runs a gauge repeatability and reproducibility study and finds that reproducibility contributes far more variation than repeatability. What does this result most likely indicate?

  1. The gauge itself is unstable across repeated readings of the same part
  2. The measurement resolution is finer than the process variation
  3. The parts selected for the study are too similar to one another
  4. Appraisers differ in how they measure or judge the parts Correct answer.

Explanation

Reproducibility reflects variation between appraisers, so a large reproducibility component points to inconsistent technique, training, or interpretation among operators. Repeatability reflects the equipment and the same-appraiser variation, and part-to-part variation is a separate component.

Question 38Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A process has a stable, normally distributed output with a mean of 50.0 and a standard deviation of 2.0. The specification limits are 46.0 and 54.0. What is the process capability index Cp?

  1. 2.00
  2. 1.00
  3. 0.67 Correct answer.
  4. 1.33

Explanation

Cp equals the specification width divided by six standard deviations, so (54 minus 46) divided by (6 times 2.0) equals 8 divided by 12, or about 0.67. This shows the process spread is wider than the tolerance even though the mean is centered.

Question 39Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is designing a data collection plan for the Measure phase. Which element is most important to define before collecting any data?

  1. The names of the stakeholders who will receive the final report
  2. An operational definition of each measure, including how and by whom it is recorded Correct answer.
  3. The final p-value threshold for the project
  4. The statistical software package that will analyze the results

Explanation

Operational definitions ensure that everyone measures the same thing the same way, which is the foundation of trustworthy data. Software choice, significance thresholds, and distribution lists matter later but do not determine whether the data are valid.

Question 40Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A team wants to determine whether two factors, temperature and pressure, interact in their effect on yield. Which analysis directly addresses this question?

  1. A p-chart of yield over time
  2. A two-factor design with interaction terms in the model Correct answer.
  3. A chi-square goodness-of-fit test on yield categories
  4. Two separate one-sample t-tests on yield at each factor level

Explanation

An interaction exists when the effect of one factor depends on the level of another, which is tested by including an interaction term in a multi-factor model. Separate one-factor tests cannot detect interactions, and goodness-of-fit and control charts address different questions.

Question 41Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is analyzing cycle time data that are strongly right-skewed with several extreme values. Which measure of central tendency best represents the typical cycle time?

  1. Mean
  2. Standard deviation
  3. Median Correct answer.
  4. Range

Explanation

The median is resistant to skew and outliers because it depends on rank position rather than magnitude, so it better represents a typical value in a skewed distribution. The mean is pulled toward the long tail, and standard deviation and range measure spread rather than center.

Question 42Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is planning a multi-vari study to understand variation in a molded part dimension. Which sources should the study deliberately include?

  1. Only the variation between the two shifts with the largest difference
  2. Within-part, part-to-part, and time-to-time variation Correct answer.
  3. Only the variation attributable to the measurement gauge
  4. Only the total variation across the entire shift

Explanation

A multi-vari study deliberately samples across several nested sources, such as positions within a part, parts within a lot, and lots over time, to see which family of variation dominates. Studying only the total, a selected pair, or the gauge alone would miss the structure of the variation.

Question 43Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A team is evaluating a proposed solution and wants to confirm that it will actually address the verified root cause before full implementation. Which action best fits the Improve phase?

  1. Document the current process with a flowchart
  2. Run a pilot and compare results against the baseline with a statistical test Correct answer.
  3. Write a business case and submit it for funding approval
  4. Recompute the process sigma level from historical data

Explanation

A pilot tests the countermeasure on a limited scale and uses data to confirm that the verified root cause has been addressed before full rollout. Business cases, current-state mapping, and historical sigma calculations belong to earlier phases or to project justification.

Question 44Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is standardizing an improved process so the gains persist after the project closes. Which control approach best supports this goal?

  1. Extend the pilot for another six months before deciding
  2. Update the standard work instructions and train operators, then audit adherence Correct answer.
  3. Add a second approval step for every transaction
  4. Increase inspection frequency at the final station

Explanation

Sustaining gains requires embedding the new method in standard work, training the people who perform it, and auditing that the standard is followed. More inspection, extra approvals, and indefinite piloting add cost or delay without locking in the improved method.

Question 45Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is coaching a team that keeps proposing countermeasures before any data have been collected. Which response best reflects the DMAIC discipline?

  1. Replace the team's ideas with a benchmark from another industry
  2. Ask the team to verify the suspected cause with data before selecting a countermeasure Correct answer.
  3. Escalate the team's behavior to the project sponsor immediately
  4. Let the team implement its preferred idea and evaluate it later

Explanation

DMAIC requires that causes be verified with evidence before solutions are chosen, so the coach should redirect the team to confirm the suspected cause. Implementing first and evaluating later inverts the logic, escalation is premature, and borrowed benchmarks are not a substitute for verifying the local cause.

Question 46Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A process has a stable mean of 100 and standard deviation of 5, with specification limits of 85 and 115. The process mean then shifts to 103 while the standard deviation stays at 5. Which statement about capability is correct?

  1. Cp is unchanged while Cpk decreases Correct answer.
  2. Both Cp and Cpk decrease by the same amount
  3. Cpk is unchanged while Cp decreases
  4. Both Cp and Cpk remain unchanged

Explanation

Cp depends only on the spread relative to the tolerance width, so a shift in the mean leaves it unchanged. Cpk accounts for centering, so moving the mean toward one specification limit reduces the distance to that limit and lowers Cpk.

Question 47Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt must choose between a kanban replenishment system and a scheduled push system for a component with highly variable daily demand and short replenishment lead time. Which reasoning is most sound?

  1. Kanban should be avoided because it cannot handle any demand variation
  2. A push system is better because variability requires large planned batches
  3. The choice is irrelevant because both systems produce identical inventory levels
  4. Kanban suits this case because short lead time allows small buffers to absorb demand variation Correct answer.

Explanation

Pull systems work well when replenishment lead time is short enough that a small, capped buffer can respond to actual consumption even under variable demand. Push systems with large batches increase inventory and delay, and the claim that kanban cannot tolerate variation ignores how buffers are sized.

Question 48Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is interpreting a regression model predicting delivery time from order size and distance. The overall model is significant, but the residual plots show a funnel shape that widens as fitted values increase. What is the most appropriate conclusion?

  1. The model is invalid because a funnel shape proves the predictors are unrelated to the response
  2. The constant-variance assumption is violated, so standard errors and p-values may be unreliable Correct answer.
  3. The funnel shape confirms that the residuals are normally distributed
  4. The model should be accepted because overall significance overrides residual patterns

Explanation

A funnel-shaped residual plot indicates non-constant variance, which violates a key regression assumption and can distort standard errors, confidence intervals, and p-values. It does not by itself show that the predictors are unrelated, and it says nothing favorable about normality.

Question 49Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

A Green Belt is leading a team through a cause-and-effect analysis and wants to move beyond brainstorming opinions. Which approach best strengthens the analysis?

  1. Vote on the most popular cause and proceed directly to solution design
  2. Include only causes that the process owner already believes are important
  3. Verify the candidate causes on the fishbone diagram with data before committing to any of them Correct answer.
  4. Select the cause that is easiest to fix and begin implementation

Explanation

A fishbone diagram generates hypotheses; those hypotheses must be tested against data so that the team acts on a verified cause rather than the most popular or convenient one. Voting, choosing by ease, or restricting input to existing beliefs short-circuits that verification.

Question 50Lean Six Sigma Green Belt Practical (domain structure not published on the retrieved page)

In a Lean Six Sigma DMAIC project, which deliverable belongs specifically to the Define phase gate rather than to later phases?

  1. A documented control plan with reaction rules
  2. A statistically confirmed root cause verified with data
  3. A validated measurement system analysis for the key output
  4. A signed charter with problem statement, scope boundaries, and measurable goal Correct answer.

Explanation

The Define gate is passed when the charter is approved and the problem, scope, goal, and team are agreed; these authorize the project to proceed. Measurement system studies, root cause verification, and control plans are outputs of Measure, Analyze, and Control respectively, so they cannot close the Define gate.