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Math Help - Probabilty for a fair game problem w. binomials

  1. #1
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    Probabilty for a fair game problem w. binomials

    A 1 dollar bet is made in las vegas, if you roll two dice and it lands a 7 las vegas will pay you 5 dollars.

    if you play twelve times What is the probability you'll win twice?
    what is the probability that your first win will be on the fifth roll?
    before the fifth roll?
    if you play 12 times what is the probability you'll win 3 or more times?
    if you play 120 times what is the portability of breaking even
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  2. #2
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    This is just a question. What do you need help with, what don't you understand, what have you attempted on you own.

    I'm not a fan of "rules" myself - but it does tweak me when folks assume this is just a repository for people to do their work for them.
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  3. #3
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    I apologize. okay so i have figured that the probability of rolling a seven is .1667 with the dice. because 6 out comes for 7 and 36 total 6/36.

    now concluding this i have used my TI calculator to complete the binomial instructions canceling the theoretical way of doing it and completing it faster.

    so i have dont this for the first one Binomialpdf(12,.1667,2)
    which meant 12 times playing, the probabilty and winning twice i believe thats how you do it im not too sure..

    not it says the win will be on the fifth roll im not sure if the same aspect goes just replace the 2 for a 5.

    I have no idea how to break even and

    for fair game i have come up with this

    5(.1667)-1=-.1665 makign it not a fair game

    thats all im aware of ...
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  4. #4
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    How far into statistics are you? What level is this?

    This problem isn't asking you to just use binomial distributions. You also need to use the Geometric distribution, as well as knowing how to calculate expected values. The last one you get get to later, but do you at least know how to calculate using the Geometric distribution.

    And yes, the TI-83 is great to use, but if you don't know the WHYS behind the equations, how can you know when you are making a mistake or getting an answer that couldn't possibly be right?

    EDIT: I take that back. For the second question, you only need to know the Binomial distribution and the rules of multiplication for probabilities. Try to reason the second problem out in your head. Imagine what the experiment is doing by actually going through the motions in your head (literally throwing the dice), and then putting the outcomes into words. That is the best way to start conceptualizing some of this material so that its not just numbers you are typing into a TI-83.
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  5. #5
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    alright. well this is advanced placement stats. for 12th grade. fairly complicated for me because i only had a background of basic algebra 1 , 2 and geometry. but im doing fine in the class i just have problems doing a couple of the questions. i understand it requires some geometric and binomial. i just really dont know where to start... and my teacher isnt the best teacher in the world he teaches us to use the calculator and doesnt really want to teach the theoretical way of doing it so i just follow so i can get the grade.
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  6. #6
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    All you need is algebra to work with these problems, as they only involve exponents.

    Your method for figuring out the first one is correct. Simply use the Binomial distribution with parameters 12, 1/6.

    For the second one think of it at two independent events: the event that you roll the dice four times and don't get the required combination AND the event that you throw it again and you get the required combination. You should see that it is a Binomial multiplied by a Bernoulli trial. Two separate events (even though it covers someone throwing something five times).

    For your third problem they are asking you what is value of P(3 or more times). Well this would be TEDIOUS to calculate by hand (even using a calculator). So try using the COMPLIMENT of this event. You will only have to make three calculations (well four, but subtracting a number from one shouldn't be a problem).
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  7. #7
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    thanks you. I've figured it out.. the only one i havent figured out was breakign even.. any ideas on that?
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