The answer is 12.
Do NOT simply give out the answer. In fact, don't give the answer at all in the homework section! (Not even a wrong answer! The question was about the standard deviation, not the mean.)
(Editted by HallsofIvy)
Homework Statement
In a recent survey, 80% of the community favored building a police substation in their neighborhood. If 15 citizen are chosen, what is the standard deviation of the number favoring the substation?
Homework Equations
I know that my mean is 15 and the probiblilty is 80...