In a normal distribution, 95 percent of the data lie within how many standard deviations from the mean?

In a normal distribution, 95 percent of the data lie within how many standard deviations from the mean?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (B)

In a normal distribution, the spread of values around the mean follows a predictable pattern known as the 68-95-99.7 rule. This rule tells us that about 68% of data fall within one standard deviation of the mean, about 95% fall within two standard deviations, and about 99.7% fall within three. Therefore, to capture roughly 95% of the data, you look at two standard deviations from the mean. If you want the precise cutoff, it’s actually about 1.96 standard deviations, but two is the standard rounded answer.

In a normal distribution, the spread of values around the mean follows a predictable pattern known as the 68-95-99.7 rule. This rule tells us that about 68% of data fall within one standard deviation of the mean, about 95% fall within two standard deviations, and about 99.7% fall within three. Therefore, to capture roughly 95% of the data, you look at two standard deviations from the mean. If you want the precise cutoff, it’s actually about 1.96 standard deviations, but two is the standard rounded answer.