Some Probability Distributions

Probabilities for a binomial random variable X are calculated using the commands dbinom and pbinom.

The probability of 3 successes in n = 10 trials with a success probability p = 0.25 is computed by

dbinom(3, size = 10, prob = 0.25)

The command pbinom computed cumulative probabilities. The probability of three or fewer successes in n = 10 trials with a success probability of p = 0.25 is computed as

pbinom(3, size = 10, prob = 0.25)

The functions dpois and ppois compute probabilities and cumulative probabilities for a Poisson distribution. The probability that a Poisson random variable with mean 0.5 equals ne is given by

dpois(1, lambda = 0.5)

The cumulative probability that a Poisson random variable with mean 0.5 is at most one is given by

ppois(1, lambda = 0.5)

Try some examples of your own in the work area below.

Work Area

Enter your own commands here; then click the Submit button.