The Binomial Distribution


the binomial distribution is a common type of probability distribution for discrete random variables which obeys certain conditions.

  • there are only two possible outcomes (usually called successes or failures)
  • there are a fixed number of trials (n)
  • each trial must be independent of the other trials
  • the probability of success (π) is fixed at each trial

binomial probabilities can be found using a formula or from tables.

the mean and variance of a binomial distribution can be found using formulae.

Key Skills

  • calculate binomial probabilities using formulae and tables
  • find means, variances and standard deviation for binomial probability distributions


binomial distribution, outcomes, trials, variancestandard deviationmean.