I'm trying to remember simple probability form high school. I'd like to know how the probability of any one event changes with frequency. So for example the probability of getting one ace of spades is 1/52; what is the probability of getting at least one ace of spades if the card is put back and reshuffled over two events? How many events do you need to get a 90% probability of getting the ace of spades? I think the formula is this: 1- (51/52)^n where n is the number of times you try. 51/52 because that the chances of your event not happening. So I get 119 attempts gives you a 90% probability of getting at least one ace of spade. Am I right? Also regarding the terminology is this the cumulative probability ?