The addition rule in probability states that, for two events E1 and E2, the probability that one or the other of the events (possibly both) occurs is given by:

P(E1 or E2) = P(E1) + P(E2) - P(E1 and E2)

Program a calculator function that accepts the probabilities of E1, E2, and (E1 and E2) and then calculates the probability (E1 or E2) according to this formula.

However, there are a couple of things you should check:

All probabilities should be between 0 and 1

• The probability that events E1 and E2 both occur should not be greater than the probability of either of the individual events.