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- 2011-7-11
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- 2013-8-23
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I'm not sure if my method is right, I just remember estimating it from college stats class.
We know that in a normal distribution:
68% is +/- one standard deviation
95% is +/- two standard deviations
99% is +/- three standard deviations
so at 99% there is a range of six standard deviations
480,000-230,000 = 250,000
250,000/6 = 41,666 |
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发表于 2011-7-11 18:38
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