13. Roll two dice. Let A = "the sum is even," and B = "the sum is divisible by 3," i.e., B = {3, 6, 9, 12}. Are A and B independent?

20. Marilyn vos Savant claimed in her May 5, 2013 column that among the four digit numbers 0000 to 9999, exactly 4000 had at least one five. Compute the number of numbers with at least one 5 by computing the probability that a randomly chosen number has no 5.

25. Three independent events have probabilities 1/4, 1/3, and 1/2. What is the probability exactly one will occur?

34. Mary knows the answers to 20 of the 25 multiple choice questions on the Psychology 101 exam, but she has skipped several of the lectures, she must take random guesses for the other five. Assuming each question has four answers, what is the probability she will get exactly 3 of the last 5 questions right?

39. The following situation comes up the game of Yahtzee. We have three rolls of five dice and want to get three sixes or more. On each turn we reroll any dice that are not 6's. What is the probability we succeed?