if a procedure meets all of the conditions of a binomial distribution except the number of trials is not​ fixed, then the geometric distribution can be used. the probability of getting the first success on the xth trial is given by ​p(x)​, where p is the probability of success on any one trial. subjects are randomly selected for a health survey. the probability that someone is a universal donor​ (with group o and type rh negative​ blood) is . find the probability that the first subject to be a universal blood donor is the person selected.