Statistics

 This problem looks at STI rates and claims that on Tiffin University campus the proportion of students who have an STI is 20%. You have a two-part question: a) If a person on the Tiffin University campus has 10 sexual partners, what is the probability that at least one of them has an STI?  Part b) What is the probability if the person has 20 sexual partners?

The formula you should be considering is: P(at least one person has an STI) = 1 - P(no partners have an STI). This converts into:

P(at least one person has an STI) = 1 - P(a single partner does not have a STI) ^ (Number of partners)