I have read that the condom effectiveness in protecting from HIV infection is around 98%. Assuming the probability of contracting HIV from a single protected encounter is 2% the probability of getting nfected after 1000 protected encounters is (I took the math from here http://books.google.com/books?id=G4...=probability hiv after n encounters&f=false): [tex] 1 - (1 - 0.02)^1000 = 0.99 [/tex]. This is a pretty high value. Is the math correct here? Thanks.