Think about the Bernoulli trial. We have experimented with five coins, but only once. As we want to work with data, it is crucial we understand experimenting once can be a little bit irrational; maybe we were tossing a coin on the street, and the wind became an obstacle, so it is essentially important to have several tries.

As you remember the definition for the Bernoulli trial it is time to move on to Binomial probability.

It is when we have a defined number of successful trials among all attempts in an experiment with two outcomes.

Example:

Tossing five coins three times. Event "Tossing a coin" has only two outcomes: head or tail.