Independent events have probabilities of occurring that don’t rely on each other. For example, if I roll two dice, the number I get on the first die doesn’t affect what number I get on the second die. They are independent events. Another example is flipping several coins at once. Say I get ‘heads’ on one coin. Does this affect at all what I get for the other coins? No! So these events – the face I get on each coin – are all independent of each other.
We can use proper mathematical notation to define what must happen for two events to be independent:
If we have two events, A and B, then this has to be true:
In English this means that if the two events are independent, I can calculate the probability of them both happening by simply multiplying the probabilities of each one happening by itself.