In a Normal Distribution, what percentage of total data points lies within three standard deviations of the mean?

• A. 68%
• B. 97%
• C. 99%
• D. 95%

Answer: (C)

In a Normal Distribution, approximately 99.7% of the data points lie within three standard deviations of the mean. This concept is part of the empirical rule, or the 68-95-99.7 rule, which states that:

• About 68% of the data points fall within one standard deviation from the mean.

• About 95% are within two standard deviations.

• Approximately 99.7% are within three standard deviations.

These percentages illustrate how data are concentrated around the mean, which is a crucial characteristic of the normal distribution. The presence of this significant percentage of data within three standard deviations indicates the distribution's central tendency and variability, reinforcing the understanding of how data behaves in a normally distributed set. This makes it easier for analysts and statisticians to predict outcomes, assess risk, and make informed decisions based on statistical data.