<PRE><B>Question 181894</B>
Human pregnancy lengths are bell-shaped with a mean of 265 days and a standard deviation of 10 days. Use the Empirical Rule to determine the percent of women whose pregnancies are between 255 and 275 days.
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255 is one standard deviation below 265.
275 is one standard deviation above 265
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The percentage of a normally distributed population that lies
within one standard deviation of the mean is 68%
Your answer: 68%
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Cheers,
Stan H.
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Using the Empirical Rule 
1.About 68% of the data lie within 1 standard deviation of the mean. 
2.About 95% of the data lie within 2 standard deviations of the mean.
3.About 99.7% of the data lie within 3 standard deviations of the mean. 
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