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-   -   Probability of finding at least 1 out of the test (https://www.askmehelpdesk.com/showthread.php?t=323205)

  • Feb 28, 2009, 02:24 PM
    rickjosh19
    Probability of finding at least 1 out of the test
    On a multiple choice test of 10 questions, each question has 5 possible answers. A student is certain of the answers to 4 questions but is totally baffled by 6 questions. If the student randomly guesses the answers to those 6 questions, what is the probability that the student will get a score of 5 or more on the test. Express your answer correct to 2 decimal places.


    I really don't know how to work this out because of 10 questions 5 possible answers is a bit confusing
  • Feb 28, 2009, 04:23 PM
    galactus
    He has to get at least one of the 6 correct in order to get the 5 score.

    Find the prob. Of getting none of the 6 correct and subtract from 1.

    The prob. Of getting a answer right is 1/5, therefore, the prob. Of getting it wrong is 4/5

    The prob of getting at least 1 correct out of 6 is

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