Binomial Distribution: The graph below gives the probability distribution of the binomial random variable for a binomial experiment with n trials and probability of success p. By moving the scroll bars you can change the values of p and n (n can be atmost 20). The blue vertical line gives the location of the expected value of the binomial random variable. The red horizantal line gives the interval (μ-σ, μ+σ), i.e., its length is twice the standard deviation (σ).