find the probabilty of choosing eather multiple of 4 or5 Solution By Inclusion-Exclusion principle, P(multiple of 4 or 5) = P(multiple of 4) + P(multiple of 5) - P(multiple of 20) If we are choosing out of the entire set of integers, this probability is equal to 1/4 + 1/5 - 1/20 = 2/5..