Here is the solution to last week’s Sunday Puzzle as collated by Andrew Stacey from MathForge
https://notes.mathforge.org/notes/published/four+squares+inside+a+rectangle+solution
I am not sure if Andrew wrote the solution himself, or is just the custodian, so apologies for a somewhat vague attribution, but I can thoroughly recommend his marvellous curation of these elegant puzzles.
We loved the solution proposed by “the_cryptographer_formerly_known_as_madness” (who, you will be unsurprised to hear is the cryptographer formally known as “Madness”) on the Forum, and that is indeed one approach. A more mathematical approach is given on the math forge page linked above, but if you have not yet tried the puzzle for yourself we would recommend thinking about it before looking at the solution.
For this week’s puzzle we thought you might like to try the following:
Alice, Bob and Claire want to play table tennis. Since there is only one table and two bats, they decide that whoever loses a game steps out for the next game to let the other person in. The players of the first game are chosen randomly. By the end of their session, Alice has played 17 games, Bob 15 and Claire 10. Who lost the second game?