# Math Help - variance and probability problem help

1. ## 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!

2. $\displaystyle n = 25, p = 0.125$

$\displaystyle \mu = np$

$\displaystyle \sigma ^2 = np(1-p)$

3. thanks!!