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Math Help - Statistics

  1. #1
    Newbie
    Joined
    Feb 2009
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    4

    Exclamation Statistics

    The question goes...

    A pharmaceutical firm has discovered a new diagnostic test for a certain disease that has infected 1% of the population. The firm has announced that 95% of those infected will show a positive test result, while 98% of those not infected will show a negative test result. What proportion of tests results are correct?

    my mind is going in circles!
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  2. #2
    Member
    Joined
    Nov 2007
    Posts
    100
    What we have here is:

    * 1% are infected
    * 99% are NOT infected

    We have to find two probabilities here:

    (1) an infected person test shows positive result (correct result): (Let A)
    It's 95% of 1% so, P(A) = 0.95 * 0.01 = 0.0095

    (2) a person who is not infected shows a negative (correct) result in the test: (Let B)
    It's 98% of 99% so, P(B) = 0.98 * 0.99 = 0.9702

    So success rate would be P(A) + P(B) = 0.9702 + 0.0095 = 0.9797
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  3. #3
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    Feb 2009
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    tytytytytytytytytytytyty

    i did not think somone would come to the rescue in time :S

    greatly appreciated!
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