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Math Help - variance and probability problem help

  1. #1
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    variance and probability problem help

    here's a question i need help solving:

    you work at a restaurant that has a promotional wheel. if a customer is there on their birthday, they can spin the wheel and possibly win a prize. the wheel is set up such that there is approximately a .125 probability the customer wins a free meal. suppose that in a given week, 25 customers spin the wheel:

    1. what is the mean number of customers that will win a free meal?
    2. what is the variance of the number of customers that will win the free meal?
    i don't get how you can get the mean and variance, when the question doesn't have a list of numbers to work with!

    any help appreciated!
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  2. #2
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    \displaystyle n = 25, p = 0.125

    \displaystyle \mu = np

    \displaystyle \sigma ^2 = np(1-p)
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  3. #3
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    thanks!!
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