We will again consider the two events that we have already examined:
Event A – drawing out a ball with stripes:
Event B – drawing out a green ball:
We now ask what the probability is that the two events will occur simultaneously. Due to the overlap between them, we can see that both Events A and B occur together only if we draw out a green ball with stripes. In other words, we are looking for the probability of the following event:

The size of the event is 1.

The size of the sample space is 5 and the container has 5 balls.
The probability that both Events A and B will occur simultaneously is therefore 1/5.