# How to calculate confidence level?!?

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#1
I've been looking all over the internet but for some reason NOONE seems to know how to deal with confidence level unless its known
So I know if you have a Confidence intival of 95% you can get margin of error
(x bar) +- z*6/root n
but what if you have standard deviation, mean and your outer limits
is there a way to calculate the % chance of landing outside an interval?
e.g.
a legal coin weighs 1 gram it is rejected from a machine if it weighs less than 0.95 grams or more than 1.05g What is the likelyhood a legal coin is rejected with standard deviation 0.02g?
Or for an example of the percentage going to one side, if 50 home consume 1MW with a standard deviation of 0.2MW what is the Probability they will consume more than 1.06MW?

Is there a formula/ a way to rearrange it?
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