Within what percentage of data does ±3 standard deviations account for?

In a normal distribution, the empirical rule, also known as the 68-95-99.7 rule, provides important insights about how data is spread around the mean. Specifically, this rule states that:

• Approximately 68% of the data falls within one standard deviation (±1 standard deviation) from the mean.
• About 95% of the data falls within two standard deviations (±2 standard deviations) from the mean.
• Nearly 99.7% of the data lies within three standard deviations (±3 standard deviations) from the mean.

Therefore, when considering the range that ±3 standard deviations covers, it is correct to say that this accounts for about 99.7% of the data in a normal distribution. This significant portion indicates that most data points are concentrated close to the mean, with only a few extreme values falling outside this range. Understanding this concept is crucial for interpreting statistical data and managing laboratory results, where it helps in identifying outliers or unusual patterns that may require further investigation.