This equation computes the probability that two events will both happen.  The inputs to this equation are the probability of event A and the probability of event B.

Notes

The probability that two events, event A and event B, may both occur is the product of their probabilities.

If there are half boys and half girls in a group of  ten students, the probability of picking a girl, P(A) is 0.5, or 5 in ten.

If in the same group there is one person wearing a read shirt, then the probability, P(B) is 0.1, or 1 of ten.

If there is a random selection from the group, the probability that that selection will pick a girl wearing a red shirt, P(A and B), is equal to `P(A) * P(B) = 0.5 * 0.1 = 0.05`