If a trial of an experiment can result in success with probability p and failure with probability q (i.e.1-p) the probability of exactly r success in n trials can be determined by Bernoulli theorem. .The formulae used is as follows:
Here, n = number of experiments
R= number of success in the definite experiments
P= probability of success in an experiment and
Q= 1-p= the probability of unsuccess in the experiments.