Consider independent flips of a coin, where the probability of heads is 0.03. The experiment is to flip the coin until we get ou
r first heads. The random variable is the total number of flips we had to make to get that first heads. What is the expected value of this random variable
because we're stopping at the first success (which in this case is a heads), trails and independent, and these are bernouli trial's this is what you call a geometric distribution
The expected value of a geometric distribution (where we are counting the number of trails) is 1/p