it's actually a question related to standard deviation. first, u need to understand what the standard deviation is. half of 68% is the mark ranging from the average 86 to 92 (average plus the the standard deviation 6) the question is asking about the percentile of 92 and lower.. 50%-68%/2 is the percentile of 92 and higher... Thus, u juz need to subtract the above percentile from 100% to get the results of the percentile of 92 and lower :')
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发表于 2011-6-28 21:57:15
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