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Statistics, probability help please !

  1. Jul 6, 2011 #1
    1. The problem statement, all variables and given/known data

    In a certain high-risk group, the chance of a person having suffered a heart attack is 70%. If four persons are chosen from the group, find the probability that at least one will have had a heart attack.

    2. Relevant equations

    (work shown below) these would be dependent

    3. The attempt at a solution

    (.7)/(4) = 2.8
     
  2. jcsd
  3. Jul 6, 2011 #2
    It might be easier to think of the chance that a specific individual doesn't have a heart attack, so what are the chances that none of the individuals have heart attacks (and you might want to rethink the dependence).
     
  4. Jul 6, 2011 #3
    your answer is wrong



    i don think it is a dependent event

    the probability of a person with heart attack is 0.7

    so the probability that among 4 at least 1 has heart attack = 1 - probability that none have

    = 1 - (0.3)[itex]^{4}[/itex]



    must be correct but verify it
     
  5. Jul 6, 2011 #4
    Amateur's answer is correct.

    Your attempt doesn't make any sense.
    Remember: probability can never be more than 1.

    So if you find 2.8, think again.
     
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