Andy Capp has told Flo that he will go to the pub only if he gets a Head when he tosses a coin, so he is tossing a coin until the first Head comes up. Let X be the number of tosses needed. Does X have a Binomial distribution? If not why not? I assume that they haven\'t given us the number of trials so it cannot be, but then X is the number of trials, and now i\'m confused! Help please. Solution X has a geometric, not a binomial, distribution. Note that if X represented, say, the number n of times Andy tossed heads during k trials, it would be a binomial distribution with parameters (n, k), and P(X = n) would be maximized for some median value around n = k / 2.