Posted by Lisa on .
in a health study, 18% of americans are underweight. If 4 americans are randomly selected, what is the probability that at least one will be underweight?

probability 
Reiny,
prob(underweight) = .18
prob(NOT underweight) = .82
Prob(at least one underweight)
= 1  prob(all 4 not underweight)
= 1  .82^4
= .5478..
or appr 55%
here is a more detailed version of your question back from 2009
http://www.jiskha.com/display.cgi?id=1233928692 
probability 
Lisa,
Thank you so much for taking the time to help me.