I'd like to know how to find the probability of an event occurring, given the probability of that event, within a certain number of chances for it to occur.
For example, say that once every year there is an event that can either occur or not. There is a 1/5,000,000 chance of that event occurring during that year. You live 60 years. What is the probability that of one of those events will occur during your lifetime?
Best Answer
$$Pr[X \text{ occurs at least once in sixty years }]$$ $$ = 1 - Pr[X \text{ occurs never in sixty years}] = 1 - Pr[X \text{ does not occur in a given year}]^{60}$$ $$ = 1-(1-1/5 000 000)^{60}$$