Let X be the random variable denoting ‘Number of trials to get a first success’. The success can occur in the 1st trial.
∴ The probability of success in the 1st trial is p. The success in the 2nd trial means failure in the 1st trial.
∴ Probability is qp.
Success in the 3rd trial means failure in the first two trials. Probability of success in the 3rd trial is q2p.
As it goes on, the success may occur in the nth trial which mean the first (n – 1) trials are failures. probability = q(n - 1) p.
∴ The probability distribution is as follows
