Lean Six Sigma Green Belt Certification Basic Statistical Tools 2

Question 1

A dataset has a mean of 50 and a standard deviation of 5. What is the coefficient of variation (CV)?

Accepted Answer

10%

Answer

CV = (standard deviation / mean) × 100 = (5 / 50) × 100 = 10%.

Question 2

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

Accepted Answer

95%

Answer

The empirical rule states approximately 95% of data falls within ±2 standard deviations.

Question 3

Which measure of central tendency is most resistant to extreme outliers?

Accepted Answer

Median

Answer

The median is resistant to outliers because it is based on rank order, not the actual values.

Question 4

A process produces parts with diameters measured at 10.1, 10.3, 9.8, 10.5, and 10.3 mm. What is the range?

Accepted Answer

0.7 mm

Answer

Range = maximum − minimum = 10.5 − 9.8 = 0.7 mm.

Question 5

What type of data results from counting defects per unit?

Accepted Answer

Attribute data

Answer

Counting defects produces discrete attribute (count) data, not continuous variable data.

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