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Homework Help: Statistics, probability help!

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

    The probability of Mr. Jones being selected for jury duty is 70%. The probability that Mr. Smith will be selected is 40%. The probability that neither will be selected is 10%. What is the probability that both are selected?

    2. Relevant equations

    the "and" rule

    3. The attempt at a solution

    (.4) + (.7) - (.1) = 1
     
  2. jcsd
  3. Jul 6, 2011 #2
    first of all i think you should get a good book on probability since most of the problems posted by you are quite basic and you seem to be guessing the answers..

    in this question

    given is

    P(A) = 0.7
    P(B) = 0.4
    P(A[itex]^{c}[/itex][itex]\cap[/itex]B[itex]^{c}[/itex])= 0.1

    you have to find P(A[itex]\cap[/itex]B)

    use

    P(A[itex]^{c}[/itex][itex]\cap[/itex]B[itex]^{c}[/itex]) + P(A[itex]\cup[/itex]B) =1
     
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