Coupon Collector's Problem

Coupon Collector's Problem
Expected ValueMedium

There are N distinct types of coupons in cereal boxes and each type, independent of prior selections, is equally likely to be in a box.

  1. If a child wants to collect a complete set of coupons with at least one of each type, how many coupons (boxes) on average are needed to make such a complete set?
  2. If the child has collected n coupons, what is the expected number of distinct coupon types?

Compute for N=6 and n=6