Collecting Coupons: Coupons in cereal boxes are numbered 1 to 5, and a set of one of each is required for a prize. With one coupon per box, how many boxes on the average are required to make a complete set?
这是《Fifty Challenging Problems in Probability with Solutions》书中的第14个题目[1]。在第一个盒子中，我们得到其中一个数字[......]