Khan/khan-exercises — Issue #12961: Standard deviation - incorrect calculation of standard deviation
Author: KhanBugz
Created: 2012-02-03 01:42:47+00:00
State: open
Labels: firefox, win7, wrong-or-unclear

Reporter: kyeegray@gmail.com

The standard deviation is calculated by taking the sum of the variance divided by n-1, not n as is used in this problem.

[standard_deviation.html?seed=147&problem=population](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/standard_deviation.html?seed=147&problem=population&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/standard_deviation.html?seed=147&problem=population&debug&activity=%5B%5B%22incorrect-activity%22%2C%22%5B%5C%229%5C%22%2C%5C%225.2%5C%22%5D%22%2C67%5D%2C%5B%22hint-activity%22%2C%220%22%2C59%5D%2C%5B%22hint-activity%22%2C%220%22%2C64%5D%2C%5B%22hint-activity%22%2C%220%22%2C67%5D%2C%5B%22hint-activity%22%2C%220%22%2C68%5D%2C%5B%22hint-activity%22%2C%220%22%2C78%5D%2C%5B%22hint-activity%22%2C%220%22%2C86%5D%2C%5B%22hint-activity%22%2C%220%22%2C96%5D%2C%5B%22hint-activity%22%2C%220%22%2C104%5D%2C%5B%22hint-activity%22%2C%220%22%2C108%5D%2C%5B%22hint-activity%22%2C%220%22%2C110%5D%5D)

[["9","5.2"]]

Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.12) Gecko/20101026 Firefox/3.6.12 (.NET CLR 3.5.30729)

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