Free Lean Six Sigma Green Belt practice test: are you ready?

5 sample Lean Six Sigma Green Belt questions, explained

From the practice tests in our guide. Try them before you open the answer.

1. 1. Six Sigma performance is conventionally expressed as 3.4 defects per million opportunities. Which statement correctly defines the basis of that figure?

   • A. The long-term defect rate of a process whose specification limits sit six standard deviations from the process mean, with a 1.5 standard deviation allowance for drift in the mean over time
   • B. The defect rate of a perfectly centered process with no shift in the mean and specification limits at six standard deviations
   • C. The proportion of finished units rejected at final inspection per million units produced
   • D. The defect rate of a process whose short-term standard deviation is one-sixth of the specification width
   Show the answer

   Correct: A (The long-term defect rate of a process whose specification limits sit six standard deviations from the process mean, with a 1.5 standard deviation allowance for drift in the mean over time).

   The 3.4 defects per million opportunities figure describes the long-term performance of a process whose specification limits sit six standard deviations from the mean, adjusted by the conventional 1.5 sigma shift that allows for mean drift over time. Option D describes a process with a short-term capability index of 1.0, and Option C confuses defects with rejected units, since a single unit can carry more than one defect.

   Topic: The Lean Six Sigma System, Origins, Belts and the DMAIC Roadmap

2. 2. A supervisor writes a list of the eight wastes on a whiteboard: Defects, Overproduction, Waiting, Non-utilized talent, Transportation, Inventory, Motion, and Downtime. Which statement correctly evaluates this list?

   • A. The list is inaccurate, because the eighth waste is extra-processing and downtime is not one of the eight.
   • B. The list is accurate, because downtime is the eighth waste and captures unplanned machine stoppages.
   • C. The list is accurate, because downtime is simply the shop floor name for waiting.
   • D. The list is inaccurate, because the final waste is excess inventory rather than downtime.
   Show the answer

   Correct: A (The list is inaccurate, because the eighth waste is extra-processing and downtime is not one of the eight.).

   Downtime is a familiar word that nearly matches the DOWNTIME mnemonic and is a frequent distractor, but it is not one of the eight wastes. The final waste is extra-processing, which is work performed on a product or document beyond what the customer requires or will pay for.

   Topic: Lean Thinking, The Eight Wastes, Flow and Daily Improvement

3. 3. A team is deciding which of its four draft statements belongs in the problem statement box of the charter. Which statement is written correctly for that box?

   • A. We will reduce order entry errors from 14 per 1,000 transactions to 4 by March 31.
   • B. Order entry errors averaged 14 per 1,000 transactions over the last quarter, against a target of 4.
   • C. Order entry errors will be eliminated once the new system is installed.
   • D. Order entry errors must be reduced from 14 per 1,000 transactions to 4.
   Show the answer

   Correct: B (Order entry errors averaged 14 per 1,000 transactions over the last quarter, against a target of 4.).

   A problem statement describes the current state in past or present tense with measured data, so the statement reporting an average of 14 errors per 1,000 transactions over the last quarter against a target of 4 is correctly written. Statements phrased as we will reduce, must be reduced, or will be eliminated are future-oriented goal statements with a target and a deadline, and they belong in the charter's goal section instead.

   Topic: Define, Charters, Voice of the Customer and SIPOC

4. 4. A Green Belt has finished drawing the boxes, decisions, and arrows of a five-step order-entry map and now wants the map to show where the process loses time. Which two values should be written next to every step on the map?

   • A. Takt time and total lead time
   • B. Defect count and rework hours
   • C. Cycle time and queue time
   • D. Value-added ratio and rolled throughput yield
   Show the answer

   Correct: C (Cycle time and queue time).

   Annotating each step with cycle time and queue time is what converts a diagram of sequence into a waste-finding instrument, because it prices the waste in minutes of work against minutes of waiting. Takt time, total lead time, defect counts, and yield figures are whole-process measures and are not the per-step annotations the map requires.

   Topic: Measure, Process Mapping, Data Collection and Measurement System Analysis

5. 5. A Green Belt has 14 delivery times sorted from smallest to largest and needs the median. Which rule gives the correct median?

   • A. The average of the 6th and 7th values in the ordered list
   • B. The 7th value in the ordered list
   • C. The average of the 7th and 8th values in the ordered list
   • D. The average of the smallest and largest values in the ordered list
   Show the answer

   Correct: C (The average of the 7th and 8th values in the ordered list).

   With an even number of ordered values there is no single middle value, so the median is the average of the two center positions. In a list of 14 those positions are the 7th and 8th values, while taking the 7th value alone treats an even-count list as though it had a single center point.

   Topic: Descriptive Statistics and Probability, Reading Data Before You Test It

Frequently asked questions

Is this Lean Six Sigma Green Belt practice test free?

Yes. It is free, it needs no account, and you see your result immediately.

How is the readiness verdict calculated?

80% or more correct = ready, 65-79% = almost, below 65% = not yet. It is a conservative bar for practice, not the official passing score of the exam.

Where do the questions come from?

From the practice tests in our Lean Six Sigma Green Belt study guide, mixed across every topic of the exam: 25 questions per attempt. The sample questions on this page are not repeated in the test.