Timothy Chow’s Amazing Fifteen Boxes Puzzle (TYI 56)

from blog Combinatorics and more, | ↗ original
TYI56 asked the following question of Timothy Chow: You have fifteen boxes labelled with the English letters from A to O. Two identical prizes are placed in two (distinct) boxes chosen at random. Andrew’s  search order is  ABCDEFGHIJKLMNO. Barbara’s search … Continue reading →