Example:
What happens if we want to throw 1 and 6 in any order? This now means that we do not mind if the first die is either 1 or 6, as
we are still in with a chance. But with the first die, if 1 falls uppermost, clearly It rules out the possibility of 6 being uppermost, so
the two Outcomes, 1 and 6, are mutually exclusive, One result directly affects the other. In this case, the probability of throwing 1
or 6 with the first die is the sum of the two probabilities, 1/6 + 1/6
= 1/3.
When two events are mutually exclusive,(they can't happen at the same time) the probability of one or the other happening is the sum of the probabilities of each event.