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English translation from Chinese
Find the specified area using a standard normal table.
Between one standard deviation below the mean and two standard deviations above the mean.
(Round to four decimal places as necessary.
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Use the empirical rule.
Between one standard deviation below the mean and two standard deviations above the mean, the area is
+ = 0.34 + 0.475 = 0.815, approximately.
Solved.
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The Empirical Rule states that 68% of the data falls within one standard deviation,
95% percent within two standard deviations, and 99.7% within three standard deviations from the mean.