LSS Green Belt practice questions: Measure

5 free questions from 30 on this area · answer and explanation for each · no sign-up

These 5 questions come from the Measure section of our LSS Green Belt bank (30 questions on this area, which carries 20% of the real exam). Every question is original, with the correct answer explained and linked to the source it is drawn from.

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1/5 · Measure · easy

A cross-functional team brainstorming potential root causes of a rise in customer complaints organizes their ideas into branches such as Machine, Method, Material, Man/People, Measurement, and Environment. Which tool are they using?

APareto chart

BCause-and-effect (fishbone/Ishikawa) diagram

CSIPOC diagram

DFailure Modes and Effects Analysis (FMEA)

Show answer & explanation

B is correct. The cause-and-effect (fishbone or Ishikawa) diagram is a structured brainstorming tool that groups potential causes of an effect into standard categories such as Machine, Method, Material, Man, Measurement, and Mother Nature (Environment), helping teams explore causes systematically before verifying them with data.
↗ the IASSC Lean Six Sigma Green Belt Body of Knowledge (ILSSBOK, PeopleCert syllabus) — Measure

2/5 · Measure

A process output is normally distributed with a mean of 100 and a standard deviation of 5. Approximately what percentage of observations would be expected to fall between 90 and 110?

AApproximately 50%

BApproximately 68%

CApproximately 95%

DApproximately 99.7%

Show answer & explanation

C is correct. Under the empirical (68-95-99.7) rule for a normal distribution, about 68% of data falls within 1 standard deviation of the mean, about 95% within 2 standard deviations, and about 99.7% within 3. Since 90 and 110 are exactly 2 standard deviations (2x5) from the mean of 100, approximately 95% of observations fall in that range.
↗ the IASSC Lean Six Sigma Green Belt Body of Knowledge (ILSSBOK, PeopleCert syllabus) — Measure

3/5 · Measure

For a given process, Cp = 2.0 but Cpk = 0.8. What does this combination most likely indicate about the process?

ACp and Cpk always measure the same thing, so this combination is impossible and must be a data entry error

BThe process has too much variation to ever meet specifications, regardless of centering

CThe process has enough inherent spread (variation) to potentially fit within the specification limits, but the process average is not centered between the specification limits

DThe process is perfectly centered and capable, meeting all customer requirements

Show answer & explanation

C is correct. Cp compares the specification width to the process spread assuming perfect centering, while Cpk also factors in how far the process mean is from the nearer specification limit. When Cp is much higher than Cpk, as in this case (2.0 vs 0.8), the process has low variation but is significantly off-center, which is a common and important distinction tested on the exam.
↗ the IASSC Lean Six Sigma Green Belt Body of Knowledge (ILSSBOK, PeopleCert syllabus) — Measure

4/5 · Measure

A process has an Upper Specification Limit (USL) of 60, a Lower Specification Limit (LSL) of 40, a process mean of 52, and a standard deviation of 3. What is the Cpk for this process (rounded to two decimal places)?

A1.33

B1.67

C1.11

D0.89

Show answer & explanation

D is correct. Cpk accounts for how centered the process is between the specification limits by taking the minimum of the two one-sided capability ratios. Here the process mean (52) is closer to the USL side in relative terms, giving (60−52)/9 = 0.89 as the limiting value, so Cpk = 0.89, indicating the process is not well centered even though Cp = 1.11 looks better.
↗ the IASSC Lean Six Sigma Green Belt Body of Knowledge (ILSSBOK, PeopleCert syllabus) — Measure

5/5 · Measure

A process is reported as having a Cp of 1.67 but a Cpk of 0.83. What does this combination most likely indicate?

AThe measurement system used to compute Cpk is invalid and must be re-validated with a new Gage R&R study before the number can be trusted

BThe process is both well-centered and fully capable, so the low Cpk value is simply a rounding artifact that can be ignored

CThe process's overall variation is too wide relative to the tolerance, regardless of how centered its average is

DThe process has more than enough inherent spread to fit within the specification limits, but its average is shifted off-center relative to those limits

Show answer & explanation

D is correct. Cp compares the specification width to process spread assuming perfect centering, while Cpk also accounts for how far the process average is shifted from the target. A large gap between a healthy Cp and a much lower Cpk is the classic indicator of a centering (accuracy) problem rather than a spread (precision) problem.
↗ the IASSC Lean Six Sigma Green Belt Body of Knowledge — Measure

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