In a standard normal distribution, approximately what percentage of data falls within 2 standard deviations of the mean?
Answer and explanation
Correct answer: C. 95%
- Step 1: According to the empirical rule (68-95-99.7 rule) for normal distributions:
- Step 2: Approximately 68% falls within 1 standard deviation, 95% falls within 2 standard deviations, and 99.7% falls within 3 standard deviations.
Answer
95%.
Why not the others: Option 68% corresponds to 1 standard deviation. Option 99.7% corresponds to 3 standard deviations. Option 90% is a confidence level parameter, not a standard empirical rule integer sigma interval.
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