Six Sigma Black Belt Certified Practice Exam

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Prepare for the Six Sigma Black Belt exam with study materials, flashcards, and multiple choice questions. Each query comes with hints and explanations. Enhance your abilities and get ready for success!

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For a normal distribution, two standard deviations on each side of the mean would include what percentage of the total population?

The correct answer is: 95%

In a normal distribution, the empirical rule, also known as the 68-95-99.7 rule, provides a quick reference for understanding the spread of data relative to the mean and standard deviations. According to this rule, approximately 68% of the data falls within one standard deviation from the mean, about 95% of the data falls within two standard deviations from the mean, and nearly 99.7% of the data lies within three standard deviations from the mean. Therefore, when considering two standard deviations on either side of the mean, it is accurate to state that this range captures about 95% of the total population in a normal distribution. This understanding of the distribution's spread is foundational in statistics and helps in various applications, such as quality control and process improvement, which are pivotal concepts in Six Sigma methodologies. Other options do not align with the established empirical rule for a normal distribution. For example, 47% does not reflect the standard percentage associated with deviations from the mean, while 68% pertains to one standard deviation, and 99% would be closer to capturing data within three standard deviations from the mean.