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standard deviation: normal distribution

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by pemdas » Sun Mar 18, 2012 2:09 am
plz follow explanations for realistic example:
akhilsuhag wrote:The average (arithmetic mean) of a normal distribution of a school's test scores is 65, and standard deviation of the distribution is 6.5. A student scoring a 78 on the exam is in what percentile of the school?

[spoiler]OA: 98[/spoiler]
pemdas wrote:The percentages are valid for any question involving a normal distribution, and one should memorize them as 34: 14 : 2. The percentages correspond to the 1st, 2nd, and 3rd standard deviations on each side of the mean. A student scoring 78 on the exam is placed two standard deviations on the right side of the mean, that is 50% (mean) + 34% + 14% = 98%
you can find details at this link https://www.beatthegmat.com/mean-and-sta ... tml#402966
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by heymayank08 » Sun Mar 18, 2012 5:21 am
thanx..i was looking for the %age distribution that u jst gave.
i think it solves my problem :)
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