He just really needs 15 pieces of paper. And he then counts the number of windows in the room and chooses the volunteer with that number. So the question here is, is the number of windows in the room, is it random, and is it evenly distributed? So maybe you could make a case that depending on what building it's in and someone's house, it's somewhat random on how many windows that house happens to have, the house that's happening to host the birthday party. But it's not going to be evenly distributed. Most, I don't know. There's probably some, if you were to sit and plot all of the houses that had a birthday party, you'd probably see that it's more likely that they have 10 windows than one window.