probability distribution

• a random variable is a variable whose value depends on the outcome of a random event
• the range of values the random variable can take is called a sample space
• the variable is discrete it can only take certain numerical values
• the variable is random the outcome is not known until the experiement is carried out
• a probability distribution fully describes that probability of any outcome in the sample space
• when all of the probabilities are the same, the distribution is known as a discrete uniform distribution
• binomial distribution is the number of ways of choosing r items from the sample where the order of items in choice doesn't matter
• binomial distribution can be used to model the number of times a trial is sucessful
• x ~ B (n,p)