alleryStart learning →About what percentage of values lie within two standard deviations of the mean?
A99.7 percent
B50 percent
C95 percent
D68 percent
Answer & Solution
Correct answer: C. 95 percent
1. The empirical rule assigns a percentage to each distance from the mean.
2. About 95 percent of the x values lie within two standard deviations of the mean.
3. The z-scores at those two points are minus 1 and plus 1 for one deviation, and minus 2 and plus 2 for two.
4. 68 percent is the figure for one standard deviation instead.
_Source: OpenStax Introductory Statistics 2e (CC BY 4.0), Ch 6 'The Normal Distribution', sections 6.1-6.3_
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