Learning Resources

Focus C: The Addition Principle

Test yourself (Answers)

Let event A be "snow on May 24th" and let event B be "snow on November 11th." Then, using the formula we get:

                             P(A  or  B)  = P(A)  +  P(B)  - P(A  and  B)
                                                = 0.45  +  0.60  -  0.15
                                                = 0.90

The probability of having snow on at least one of these weekends is 90%.