Futility Closet offers another interesting puzzle:
“A billiard ball is resting on a table that measures 10 feet by 5 feet. A player hits it with no ‘English’ and it strikes four different cushions and returns to its starting point. University of Alberta mathematician Murray Klamkin asks: How far did it travel?”
After solving the problem myself, I verified that Futility Closet provides an answer, but without real justification. So I thought I would write up my solution. See Pool Party.