SOLUTION: In one city 21% of adults smoke. In groups of size 130 adults, what is the variance of the number that smoke?

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Question 666272: In one city 21% of adults smoke. In groups of size 130 adults, what is the variance of the number that smoke?
Answer by swincher4391(1107) About Me  (Show Source):
You can put this solution on YOUR website!
You either smoke or you don't smoke. This screams binomial distribution.
The variance of a binomial is npq where n =130 and p = .21 (q = .79)
Then the variance is 130*.21 * .79 = 21.567.
Hope this helps!