Lean Six Sigma Green Belt Certification Lean Six Sigma Green Belt Basic Statistical Tools 1

Question 1

In a normal distribution, approximately what percentage of data falls within two standard deviations of the mean?

Accepted Answer

95.4%

Answer

The empirical rule states that ~68% of data falls within ±1σ, ~95.4% within ±2σ, and ~99.7% within ±3σ of the mean in a normal distribution.

Question 2

A scatter diagram is primarily used to:

Accepted Answer

Identify the relationship between two continuous variables

Answer

A scatter diagram plots paired data points to visually reveal whether a relationship (positive, negative, or none) exists between two continuous variables.

Question 3

Which of the following best describes a process capability index (Cp) value of 1.33?

Accepted Answer

The process is centered and highly capable

Answer

A Cp of 1.33 means the process spread fits within the specification limits with adequate margin (process width is 75% of the spec width), indicating a capable process. Cp does not account for centering—that is Cpk.

Question 4

What does a p-value less than 0.05 indicate in hypothesis testing (assuming α = 0.05)?

Accepted Answer

The result is statistically significant and we reject the null hypothesis

Answer

When the p-value is less than the significance level α (0.05), the evidence against the null hypothesis is strong enough to reject it, meaning the result is statistically significant.

Question 5

In a box plot (box-and-whisker plot), what does the line inside the box represent?

Accepted Answer

The median (50th percentile)

Answer

The line inside the box of a box plot marks the median (Q2 or 50th percentile). The box itself spans from Q1 (25th percentile) to Q3 (75th percentile), representing the interquartile range.

Lean Six Sigma Green Belt Certification Practice Test

Lean Six Sigma Green Belt Certification Practice Test

Lean Six Sigma Green Belt Certification Lean Six Sigma Green Belt Basic Statistical Tools 1