What percentage of data falls within 2 standard deviations?

• A. 95% of data
• B. 68% of data
• C. 99.7% of data
• D. 50% of data

Answer: (A)

In a normal distribution, data spread around the mean follows the 68-95-99.7 rule. About 68% lie within one standard deviation of the mean, and about 95% lie within two standard deviations. The idea is that most of the data sits close to the center, and as you measure farther from the mean, you capture a large majority of the data by the time you reach two standard deviations.

So, the option that says 95% is the best answer because it matches the interval within two standard deviations. The 68% option would be within one standard deviation, and the 99.7% option corresponds to three standard deviations. The 50% figure doesn’t align with this standard rule.