Binomial Distribution

The binomial distribution is a way to determine the probability of a certain number of successes happening in a fixed number of attempts.

For example, with a long, four-day weekend coming, there's a 20% chance of rain each day. We could use the binomial distribution to determine how likely it is that we have rain-free days on three of the four days.

Before we start trying to calculate this probability all willy-nilly, we need to make sure there are only two possible outcomes each time we make an attempt, that the probability of success (and failure) remain the same for each attempt, that we know how many attempts we're going to make before we start calculating anything, and that one attempt does not affect the outcome of any other attempt.

Think of those conditions as hoops that must be hopped through in order to appease the binomial distribution gods, who will then bless us with a correct probability.