IASSC Certified Lean Six Sigma Black Belt (ICBB) — Question 7

Using this partial Z Table, how many units from a months production run are expected to not satisfy customer requirements for the following process?
Upper specification limit: 7.2 Lower specification limit: 4.3 Mean of the process: 5.9 Standard Deviation: 0.65 Monthly production: 450 units

Answer options

• A. 3
• B. 7
• C. 10
• D. 12

Correct answer: C

Explanation

The expected number of non-conforming units is calculated using the Z-score formula to determine how many standard deviations the upper and lower limits are from the mean. The calculations yield a total of 10 units that do not meet specifications, making option C the correct choice. The other options (A, B, D) are incorrect as they do not match the calculated non-conformance rate.