We will again consider the two events that we have already examined:

Event A – drawing out a ball with stripes:

Treatment of Two Events Occurring Simultaneously

Event B – drawing out a green ball:

Treatment of Two Events Occurring Simultaneously

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:

Treatment of Two Events Occurring Simultaneously

  • 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.