The range 1-100 is 100 numbers, divide by 4 and 5 to find the number of multiples. 100/4 = 25 100/5 = 20
probability of choosing multiple of 4 25/100 = 1/4 probability of choosing multiple of 5 20/100 = 1/5
the probabilities are not mutually exclusive because there are duplicate numbers, (overlap) multiples of both 4 and 5 being counted twice. 5/100 = 1/20 20, 40, 60, 80, 100
when "or" is used, add the probabilities, subtract the duplicates.
