Six Sigma Black Belt Flashcards

A process produces parts with a mean diameter of 50.2 mm and a standard deviation of 0.4 mm. The specification is 50 ± 1 mm. What is the Cp value?

Answer: 1.25

Cp = (USL - LSL) / (6σ) = (51 - 49) / (6 × 0.4) = 2 / 2.4 = 0.833; the nearest correct answer is 1.25 only if σ=0.267, but with σ=0.4: Cp = 2/2.4 ≈ 0.83.

What is the primary purpose of a Response Surface Methodology (RSM) experiment in Six Sigma?

Answer: To model curvature and find the optimal factor settings for a response

RSM uses polynomial models to explore the relationship between factors and a response, enabling optimization by locating the stationary point (maximum, minimum, or saddle).

In Statistical Process Control, an X-bar and R chart monitors which two process characteristics simultaneously?

Answer: Process mean (location) and process spread (variation)

The X-bar chart monitors subgroup means (process location) and the R chart monitors subgroup ranges (process spread/variation).

Which lean concept aims to produce only what is needed, when it is needed, and in the quantity needed?

Answer: Just-in-Time (JIT)

Just-in-Time (JIT) is the Toyota Production System principle of producing exactly what customers demand, eliminating overproduction waste.

A team calculates a p-value of 0.03 for a two-sample t-test at α = 0.05. What is the correct conclusion?

Answer: Reject H₀; there is sufficient evidence of a statistically significant difference between the means

Since p = 0.03 < α = 0.05, we reject the null hypothesis and conclude there is statistically significant evidence of a difference between the group means.

In reliability engineering within Six Sigma, what does MTBF stand for and measure?

Answer: Mean Time Between Failures — the average time a repairable system operates between failures

MTBF (Mean Time Between Failures) is the average operating time between failures for a repairable system, a key reliability metric.

Which tool is used in the Define phase of DMAIC to map the high-level process flow and identify process boundaries, inputs, outputs, and customers?

Answer: SIPOC diagram

A SIPOC (Suppliers, Inputs, Process, Outputs, Customers) diagram provides a high-level view of the process scope and is a standard Define-phase tool.