What percentage is one standard deviation?

Understand the Problem

The question is asking about the percentage of values that fall within one standard deviation from the mean in a normal distribution. In a standard normal distribution, approximately 68% of the data falls within one standard deviation of the mean.

More Information

According to the Empirical Rule (also known as the 68-95-99.7 rule), about 68% of the data in a normal distribution falls within one standard deviation from the mean.

Tips

A common mistake is confusing the percentage within one standard deviation (68%) with other standard deviations such as two (95%) or three (99.7%).

Sources

• Standard Deviation - Scribbr - scribbr.com
• 68–95–99.7 rule - Wikipedia - en.wikipedia.org
• Empirical Rule: Definition, Formula, Example - Investopedia - investopedia.com