Math Probability: Question Help ME Please!!?

Please open up the link below:

and teach me how to do the questions you see there. I am stuck and don't know how to start.

Please SHOW steps & FINAL answer. Best ANSWER will be given out to anyone who helps me.

1 Answer

  • 8 years ago
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    If you ask 3 people, a yes/no question of any kind,

    what are the possible numbers of "yes" responses ?

    What's the fewest, if they all answer "no"?

    What's the most, if they all answer "yes"?


    Write down all possible sequences of 3 letters

    consisting of only F and D.

    Here's half of them:

    D DD

    D DF

    D FD

    D FF

    I bet you can figure out the other four from there.

    Then since Probability(F) + Probability(D) = 1

    (since we assume there are no Martians included)

    P(D) = 1 - P(F) = 1 - .27 = .73

    Then P(some sequence of D's and F's) = individual probabilities multiplied together.

    P(DFD) = .73 * .27 * .73 = .143

    Substitute .73 for each D, and .27 for each F and multiply.

    Shortcut: all the ones with the same letters in different orders come out the same.

    Now if you have, for example, the sequence DFD,

    that is 2 D's and 1 F, so the count W = 1 in this case (for the 1 F)

    So you can

    - make an 8 row table for all the possibilities

    - and compute their probabilities

    - and count the F's in each sequence

    - and write that down on the side

    - and then add up the probabilities for each count.

    And you end up with this:

    .... Probability... W

    DDD 0.389017 0

    DDF 0.143883 1

    DFD 0.143883 1

    DFF 0.053217 2

    FDD 0.143883 1

    FDF 0.053217 2

    FFD 0.053217 2

    FFF 0.019683 3

    W: Probability

    0: 0.389017

    1: 0.431649

    2: 0.159651

    3: 0.019683

    This is called a Binomial Distribution.

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