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Math Help - Two Problems I'm working on, PLEASE check and help me by tomorrow

  1. #1
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    Question Two Problems I'm working on, PLEASE check and help me by tomorrow

    I am working on a worksheet for prob and stats now, but i want to have a referance to look at while i work. I'm not very confident in my answers.
    So can someone check my answers so far, and help me with the last so I have something to look at later if I have trouble. Thanks!!!!!

    1. Suppose we are going to have a pizza party - so we need to know how much pizza to order. We are only going to order pepperoni and hamburger pizza. We know that the probability that a person will eat at least one of these types of pizza is .94, the probability that they will eat both types is .45, and the probability that they won't eat hamburger is .35.
    A) What is the probability that a randomly chosen guest will eat hamburger pizza?
    I got .59
    B) What is the probability that a randomly chosen guest will only eat pepperoni pizza?
    I got .29
    C) What is the probabilyt that a randomly chosen guest who will eat pepperoni pizza will also eat hamburger?
    I got .61 (big guess, didn't use formula)
    D) Are the two events independent events? Justify your answer with appropriate probabilities.
    Yes (but i dont know what to put for "appropriate probabilites")

    This one I haven't attempted yet. Please could someone do it and explain it to me so I have something to look at right away after my work if I have problems????
    2. We are going to roll an 8-sided die whose numbers are 1 through 8. For each roll, if we get a multiple of 3, we win $1; if we roll an even number, we win $.50; (can only win one prize, and it would be teh largest). We don't win anything for any other value (ie $0 for anything else). Let Y=amount won.
    A) Define the PMF of Y (find f(y))
    B) Find CDF of Y (F(Y))
    C) Find E(Y) and Var(Y)

    Thanks in advance!!!!
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  2. #2
    Junior Member
    Joined
    Mar 2009
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    So far I have this for 1st... have to go eat supper though (no not pizza lol ) I may have tiome to help more.

    This is how i interpreted it,


    u may be able to go from there though
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  3. #3
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    Oct 2009
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    I see what I did wrong with 1 a) I forgot the probability that they won't eat hamburger also included the probability they don't eat any pizza (.06).

    After seeing 1 b) i can see how you manipulated the formula. I didn't know where to start with that one.

    C) i'm still not sure about.

    As for 2, I got:

    a) f(y) =
    .375 for y=0
    .375 for y=.5
    .25 for y=1

    b) f(y) =
    0 for y<0
    .375 for 0<=y<.5
    .75 for .5<=y<1
    1 for y>=1

    C) E(Y) = .4375
    Var(Y) = .152344

    And thanks for your help!!! Take your time
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