When a process has proven itself to function at a Six Sigma level this means there are less than ________ defects per million opportunities.

Question

Options

• A1.7
• B2.6
• C3.4
• D10

• A
  5% (2)
• B
  2% (1)
• C
  84% (36)
• D
  9% (4)

Explanation

Option C (3.4) is correct because Six Sigma is defined as having no more than 3.4 defects per million opportunities (DPMO), which corresponds to a process operating at 6 standard deviations (sigma) from the mean - accounting for the standard 1.5-sigma long-term process shift first identified by Motorola.

Why the distractors are wrong:

• A (1.7) and B (2.6) are not standard quality benchmarks in any recognized Sigma level framework - they appear to be plausible-looking fractions designed to mislead.
• D (10) is too high; 10 DPMO would still represent excellent quality, but it corresponds roughly to a 5.2 Sigma level, not Six Sigma.

Memory tip: Think of it as "Six Sigma = 3.4" - the number seems surprisingly small but that's the point. You can remember the pair by noting that 6 × 3.4 ≈ 20, which is close to the number of work days in a month - a quirky but sticky association. Alternatively, just anchor on "3.4 is the Six Sigma magic number" since it appears constantly in quality management literature.

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