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Math Help - Help calculating expected value (i'm not sure which distribution this is)

  1. #1
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    Question Help calculating expected value (i'm not sure which distribution this is)

    In group testing for a certain rare virus, a blood sample is taken from each of n individuals, and part of each sample is placed in a common pool. If the result on the pool is negative, no further testing would be needed. If the combined result is positive, each individual sample is tested, requiring in total n + 1 tests. If the virus is present in an individual blood sample with probability 5%, and n = 10, compute the expected number of tests needed (assume independence).

    Any help with this problem is really appreciated. thank you.
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by Intsecxtanx View Post
    In group testing for a certain rare virus, a blood sample is taken from each of n individuals, and part of each sample is placed in a common pool. If the result on the pool is negative, no further testing would be needed. If the combined result is positive, each individual sample is tested, requiring in total n + 1 tests. If the virus is present in an individual blood sample with probability 5%, and n = 10, compute the expected number of tests needed (assume independence).

    Any help with this problem is really appreciated. thank you.
    With probability 0.95 1 test is required and with probability 0.05 n+1 tests are required.

    Therefore the expected number of tests:

    E(N)=0.95 \times 1 + 0.05 \times (n+1)

    CB
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