Binomial Distribution

A binomial experiment is an experiment which satisfies these four conditions

• A fixed number of trials
• Each trial is independent of the others
• There are only two outcomes
• The probability of each outcome remains constant from trial to trial.

These can be summarized as: An experiment with a fixed number of independent trials, each of which can only have two possible outcomes.
The fact that each trial is independent actually means that the probabilities remain constant.

Examples of binomial experiments

• Tossing a coin 20 times to see how many tails occur.
• Asking 200 people if they watch ABC news.
• Rolling a die to see if a 5 appears.

Examples which aren't binomial experiments

• Rolling a die until a 6 appears (not a fixed number of trials)
• Asking 20 people how old they are (not two outcomes)
• Drawing 5 cards from a deck for a poker hand (done without replacement, so not independent)