A standard, fair die is thrown repeatedly. Let denote the number of throws before a six occurs. Choose a standard probability distribution to model this and use it to answer the following.
a) What is the probability function of .
b) Find the mean of .
c) Find the variance of .
a) I presume that this has a binomial distribution, .
b) The mean would then be
c) From what I can remember the variance is , this would give
Is this correct? The only thing I'm a bit unsure about is the part of the question that says, "before a six occurs", not sure if you have to do something different because of this?