To get the numerator of the probability: Choose the 1 black ball any of C(8,1) ways. Choose the other four red balls C(5,4) ways That's C(8,1)×C(5,4) = 8×5 = 40 ways. To get the denominator: Choose any 5 balls from the 13 in C(13,5) = 1287 ways. Probability that exactly 1 black ball is drawn =, approximately 3.1% of the time. Edwin