1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Probability of an event occurring at least once over n trials

  1. Mar 18, 2013 #1
    1. The problem statement, all variables and given/known data
    There is a 1 in 4 chance that on any given sexual encounter, Joe will contract an STD. If Joe has sex 4 times, what are the chances of him having an STD?



    2. Relevant equations

    Something with combinations maybe?

    3. The attempt at a solution

    I thought you would just add up the probability of the event happening for each trial, but that would give me 100% which isn't right.
     
  2. jcsd
  3. Mar 18, 2013 #2

    Curious3141

    User Avatar
    Homework Helper

    Something simpler. What is the complementary event to "getting STD from at least one encounter"?
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted