SOLUTION: 30% of high school students smoke tabacco. What would the standard deviation of the number of smokers be out of the 120 high students randomly selected? *I have no idea where to

Algebra ->  Probability-and-statistics -> SOLUTION: 30% of high school students smoke tabacco. What would the standard deviation of the number of smokers be out of the 120 high students randomly selected? *I have no idea where to      Log On


   

Question 612909: 30% of high school students smoke tabacco. What would the standard deviation of the number of smokers be out of the 120 high students randomly selected?
*I have no idea where to start since no mean or data is given.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
The standard deviation of a proportion is sigma+=+sqrt%28%28p%281-p%29%29%2Fn%29

This means that,

sigma+=+sqrt%28%28p%281-p%29%29%2Fn%29

sigma+=+sqrt%28%280.3%281-0.3%29%29%2F120%29

sigma+=+sqrt%28%280.3%280.7%29%29%2F120%29

sigma+=+sqrt%280.21%2F120%29

sigma+=+sqrt%280.00175%29

sigma+=+0.0418330013267

So the standard deviation is approximately 0.0418330013267