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Lean Six Sigma Green Belt – Green Belt Exam
2025 – Complete Solutions and Explanations
What is the Mean, Mode & Median for the data in Column 1, Data Set A? a. Mean = 8.7, Mode = 8, Median = 7 b. Mean = 8.7, Mode = 7, Median = 8 c. Mean = 8, Mode = 8.7, Median = 7 d. Mean = 7, Mode = 7, Median = 8. e. Mean = 8, Mode = 8, Median = 7 - CORRECT - Answer B Formula: Mean = Sum(x)/n = 8. Mode = Most frequent value = 7 Median = because sample is even (n=50), the median is the average of the (n/2)th and ((n/2)+1)th values in the sorted series = 8 Please reference Quantifying Process Variability for more information. A call center was experiencing customer complaints about time-on-hold and an improvement team was formed to solve the problem. The manager of the call center joined the team's first meeting and informed the team that their project would be short-lived because the obvious solution to the time-on-hold problem was to add more phone lines. With this advice as a basis, the team crafted a problem statement: "Additional phone lines are needed in order to reduce the average customer time-on-hold from 6.2 minutes to our target of 45 seconds". Which of the following best describes the problem statement?
a. The statement is too broad to be useful in the particular situation. b. The statement contains a solution. c. The statement is not related to the problem described above. d. This is a good problem statement. e. The statement does not fully define "time-on-hold". - CORRECT - Answer B The problem statement dictates that the solution is "additional phone lines". Please reference Project Charter for more information. What will a stakeholder analysis (RACI matrix) help the team do? a. Narrow the project scope. b. Reduce the likelihood of project roadblocks. c. Choose effective team members. d. Develop a focused problem statement. e. Choose the most optimal project to pursue. - CORRECT - Answer B A stakeholder analysis is used to 1) identify those entities that will have influence on the project, 2) identify the type of influence and 3) develop strategies to realize the positive influences and reduce any roadblocks due to the negative influences. Please reference Stakeholder Analysis - RACI Matrix for more information. When analyzing a process, which of the following terms represents the inputs? a. f(X) b. X c. Y
The business case should state the level of improvement required, otherwise, there will be no may to measure success. In addition, the economic impact should be included so that it is clear why this project is a priority vs. something else. Please reference Project Charter Toolset for more information. Which of the following is a use for a Pareto Chart? a. Determining Process capability b. Learning the vital few (most common) types of defects c. Determining significance of operator errors d. Estimating measurement error e. Determining specific trends over time - CORRECT - Answer B Pareto Charts sort occurence by order of frequency. Please reference Pareto Chart Toolset for more information. Which tool is used to convert brainstormed ideas into groups to better evaluate them? a. Spaghetti diagram b. Pareto chart c. Affinity diagram d. Quality Function Deployment e. Scatter diagram - CORRECT - Answer C Affinity Diagrams are used to sort raw information and establish recognizable groups or patterns. Please reference Affinity Diagram Toolset for more information.
This question refers to the "Claims Processing" case. A hospital processes claims and the insurance companies often reject them for coding errors. A Six Sigma team has been working on a project to reduce coding errors for the past 15 months and the data for the number and type of coding errors can be downloaded above in the "ClaimCoding" file. Use this data to answer the question below. Assuming that each claim has 20 opportunities for errors, what is the sigma level for coding errors in months 1 and 15? a. Month 1=4.7 sigma level, Month 15 = 3. b. Month 1=3.0 sigma level, Month 15 = 2. c. Month 1=4.7 sigma level, Month 15 = 3. d. Month 1=3.0 sigma level, Month 15 = 3. e. Month 1=3.0 sigma level, Month 15 = 3.3 - CORRECT - Answer E M1 DPMO=(868x1,000,000)/(716X20); M15 PMO=(605x1,000,000)/(788X20). See Sigma Level calculator for corresponding Sigma Level. Please reference Calculating the Sigma Level - Toolset for more information. This question refers to the "Claims Processing" case. A hospital processes claims and the insurance companies often reject them for coding errors. A Six Sigma team has been working on a project to reduce coding errors for the past 15 months and the data for the number and type of coding errors can be downloaded above in the "ClaimCoding" file. Use this data to answer the question below. Considering the attribute nature of code counts, what chart would you use to check whether the errors/claim are in statistical control over the time period? a. p-chart b. np-chart c. u-chart d. c-chart
d. Special cause variation e. Common cause variation - CORRECT - Answer E Variation between subgroups is noise or sampling error, called common cause variation. Please reference SPC - Control Chart Limits for more information. If your data represents % defective and you have daily samples, the size of which, although large (>50), varies from day to day, which control chart should you use? a. X-bar & R chart b. c Chart c. np Chart d. u Chart e. p Chart - CORRECT - Answer E The p chart is used for percent defective. You could also use an XmR Chart (ImR Chart). Please reference SPC Chart Selection for more information. A call center is tracking the number of seconds a caller must wait before speaking with a representative. If the measurement collected is "customers hold time", which of the following might give rise to common cause variation in the data collected. a. An occasional 'system crash', that reduce the number of operators by 50% for up to 20 minutes. b. The volume of calls received between noon and 1:00PM is three times greater than the call volume for the rest of the day. c. A wide range of experience and training among the operators. d. A flu virus in January reduces staffing at the call center by 75% for one week.
e. A new product introduction with initial quality problems leads to a spike in customer calls. - CORRECT - Answer C Answers A, B, D, and E are all things that can happen intermittently, which lends itself to special cause variation. Answer C is the only one the is inherent to the process - therefore common cause variation. Please reference SPC - Control Chart Limits for more information. A process improvement team piloted an improvement to a process that was not in control. The process specification is 8.5 units +/- 0.5 units. The results of the pilot run are shown below in an X and Moving Range chart. What conclusion can you draw from the pilot run? a. The new process is in control at an improved operating level, but the operating level has not improved - the change should not be implemented. b. The new process is not in control and the change should not be implemented because capability is still suspect. c. The new process is in control with an improved operating level and may be implemented, but additional actions are required to improve capability. d. The new process is not in control but the change can be implemented anyway to take advantage of the improvement while further actions are contemplated. e. More information is needed to be able to make any conclusions. - CORRECT - Answer C The process is in control and shows improvement on two levels after the pilot: the process mean is closer to target with a smaller variance. But the process is still not capable - before the improvement, ten out of twenty five data points were outside the specification limits; after the improvement only one is out of specification, showing a large reduction in out-of-spec parts. The team should implement the change and may continue to improve the process capability if the cost is justified. Please reference Piloting a Solution for more information. Which of the following options are the least effective control method?
number of complaints, and the cost of complaints. It also has a break-out of these complaints by cause (Note: assume one complaint per order). Your team is chartered to reduce the cost of complaints. To look at the 10 month period to see if the number of complaints as a % of orders is in statistical control, which attribute control chart should you use? a. np chart b. p-chart c. c chart d. u-chart e. Xbar-R chart - CORRECT - Answer B Varying sample size for % defective is p chart. Please reference Attribute Control Chart Toolset for more information. This question refers to the "Customer Satisfaction" case. Download the "Complaints" file above, which shows the customer complaint history for 10 months, including the number of orders, number of complaints, and the cost of complaints. It also has a break-out of these complaints by cause (Note: assume one complaint per order). Your team is chartered to reduce the cost of complaints. Construct a control chart of the complaint rate over time. What does the chart tell you about the complaint rate? (assuming that 10 points is enough data) a. It is increasing b. It is decreasing c. It is in statistical control d. Month 4 is too high and we should seek a special cause e. There are many out of control points in the chart. - CORRECT - Answer C
The chart is in control. Note: the limits on a p-chart are variable. Please reference Attribute Control Chart Toolset for more information. An improvement team has finished recording customer requirements. Which of the listed quality tools can be used to organize the data? a. Affinity diagram. b. Pareto chart. c. Run chart. d. FMEA. e. Histogram. - CORRECT - Answer A The affinity diagram is one of the best tools for organizing data. The purpose of the other tools is more for analysis than for organization or grouping. Please reference Affinity Diagram Toolset for more information. Which of the following characteristics should a data sample always have? a. The data are selected periodically (in time order). b. The data are selected randomly. c. The data reasonably represent the range of output being sampled. d. All of the above. e. None of the above. - CORRECT - Answer D A good data sample should include observations from different points in time, selected with equal probability for all items at that point in time and should reasonably cover the range of output at that point in time. Please reference Collecting Data for more information.
a. The Detection score increases b. The Occurence score decreases c. The Detection score decreases d. The Severity score decreases e. The Occurence score increases - CORRECT - Answer B If undercooking happens less frequently, the Occurence score would decrease. Detection happens after cooking, and is unaffected. Severity is also unaffected. Please reference FMEA Toolset for more information. Which of the following process measures is discrete? a. Cycle time for a billing process b. Accuracy of a single item on a credit invoice. c. Time on hold for customers calling to all centers. d. Cost for rework for a loan application. - CORRECT - Answer B Please reference Discrete vs. Continuous Measurements for more information. Of the good habits of an effective team leader, which of the following is the most important? a. Being a motivator b. Knowing the applicable statistical methods c. Setting a positive example of how you want the team to cooperate d. Making certain the team members stay in their respective areas of expertise
e. Assuring meetings start on time - CORRECT - Answer C While failure to deliver any of the options can undermine team success, serving as a role model supports all aspects of leading the team. Please reference Improving Team Development for more information. When concluding a Six Sigma project, when the team moves on and the process owner resumes control of the improved process, which of the following is NOT a key deliverable of the team? a. Control plan and updated documents for the process b. On-going measures of performance c. Sharing lessons learned during the project d. Permanent team member assigned to the process e. Operating ranges for key variables - CORRECT - Answer D Establishing and documenting a sustainable control plan includes on-going measures of performance, lessons learned and operating ranges of key variables. These deliverables, and adherence to the plan, ensure sustaining the improvements gained without requiring on-going staffing by the Six Sigma team. Please reference Ending the Project for more information. A control plan should be designed to cover which of the following areas? a. Plant financial performance and internal controls b. A single characteristic and piece of equipment c. All significant process input and output characteristics d. Separate shifts on a process e. Daily inspection and reject results - CORRECT - Answer C
Please reference Error-proofing for more information. In the statement Y=f(x), what does Y represent? a. The transfer function b. The process output of interest c. Process Capability d. An input variable e. An independent variable - CORRECT - Answer B This is true by definition. The process output (Y) is a function (f) of process inputs (Xs) Please reference Input Determines Output for more information. In which stage of a Six Sigma DMAIC project are hypothesis tests most frequently used? a. Define b. Measure c. Analyze d. Improve e. Control - CORRECT - Answer C True by common practice in application of the DMAIC process, although hypothesis testing may be used again in the Improve or Control phase to validate actions. Please reference Hypothesis Testing for more information.
Two sets of data of n=25 are compared using the t-test to test the null hypothesis that these data sets came from the same population at a 0.05 alpha level. Sample A has a mean of 25, and Standard Deviation of 0.6, while Sample B has a mean of 27 and a Standard Deviation of 0.3. Assume that the variances of the two populations are equal. Which is the correct conclusion? a. We reject the null hypothesis b. We accept the null hypothesis c. We cannot reject the hypothesis d. The means are equal e. The sample size is too small to draw any conclusions - CORRECT - Answer A The two-tailed cut-off value then is t with (25+25-2 =) 48 d.f. = +/- 2.01. A t-statistic value of - 14.91 exceeds the cut-off value of +/- 2.01, which means that the probability that they come from the same population is extremely low. Therefore, we reject the hypothesis. Please reference Comparing Two Means - t-test Toolset for more information. Internal metrics indicate that a DMAIC project team has successfully reduced the number of shipping errors, which had been a significant source of customer dissatisfaction. The project manager held a meeting with the operations manager and controller to close the project by verifying that the requirements of the project were met and terminating the project budget. What element of closing a project is missing? a. Congratulating the team on a job well done. b. Reassigning unused resources to other projects. c. Confirming the results with the company's customer. d. Writing the final project report for management review. e. Nothing, all project close-out steps were followed. - CORRECT - Answer C
c. Corrective action matrix d. Affinity diagram e. Thought process map - CORRECT - Answer D The affinity diagram is often used to organize and categorize the output of a brainstorming event. Please reference Brainstorming for more information. A process improvement team brainstorms a list of 42 improvement ideas for a particular problem. The team proceeds to multivoting to narrow down the ideas. How many votes should each team member get? a. 30 b. 5 c. 10 d. 25 e. 20 - CORRECT - Answer E Each team member should get between one-third and one-half of the ideas (14 - 21). Please reference Narrowing Down The List of Ideas for more information. Which is NOT a description of an organized and effective team? a. Team members each work with specific performance measures. b. Team members are informal about who works on what. c. Team members are selected with their complementary skills in mind. d. Team members each share accountability for the results and outcome of the project.
e. Each team member has a specific objective for their project. - CORRECT - Answer B An effective team allocates responsibilities among the team members in a mindful, organized manner. Please reference Leading Teams for more information. A Lean Six Sigma team is working to reduce the set-up time for an operating room at a hospital. All set-up activities have been identified and categorized. What is the best next step? a. Move Internal Set-up Activites to Preventive Set-up b. Move External Set-up Activites to Internal Set-up c. Move Running Set-up Activites to Shut-down Set-up d. Move Internal Set-up Activites to External Set-up e. Move External Set-up Activites to Running Set-up - CORRECT - Answer D By undertaking as many set-up activities as possible when the process is running (External Setup), process downtime is minimized during changeover. Please reference Quick Changeover Toolset for more information. A Lean Six Sigma Team wants to create a process map that will show the geographic movement of a unit through the process, along with the distance travelled through the various steps. What type of process map would be most appropriate? a. SIPOC Map b. Deployment Flow Chart c. Value-Added Flow Chart d. Spaghetti Diagram
