Khan/khan-exercises — Issue #13690: Empirical rule - Empirical Rule
Author: KhanBugz
Created: 2012-02-12 21:08:12+00:00
State: open
Labels: chrome, lion, wrong-or-unclear

Reporter: lbraschi@gmail.com

Results for exercises are way wrong; I'm calculating the correct results using R pnorm function and an independent (non-R generated) normal table, and they differ from yours in a noticeable way. For example, for this porcupine exercise it states that p(Z≤-3) = 0.15, yet the correct value for this is 0.135. If one inputs 0.135 as an answer, it gives a wrong 'wrong' result. Same goes with the other exercises.

[empirical_rule.html?seed=56&problem=shorter](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/empirical_rule.html?seed=56&problem=shorter&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/empirical_rule.html?seed=56&problem=shorter&debug&activity=%5B%5B%22incorrect-activity%22%2C%22%5C%220.135%5C%22%22%2C233%5D%2C%5B%22hint-activity%22%2C%220%22%2C2%5D%2C%5B%22hint-activity%22%2C%220%22%2C2%5D%2C%5B%22hint-activity%22%2C%220%22%2C2%5D%2C%5B%22hint-activity%22%2C%220%22%2C2%5D%2C%5B%22hint-activity%22%2C%220%22%2C2%5D%2C%5B%22hint-activity%22%2C%220%22%2C2%5D%2C%5B%22hint-activity%22%2C%220%22%2C3%5D%2C%5B%22hint-activity%22%2C%220%22%2C3%5D%2C%5B%22hint-activity%22%2C%220%22%2C3%5D%5D)

["0.135"]

Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_3) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.46 Safari/535.11

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