Steven Strogatz is back, with his second math article in the weekly NY Times series which will go for 15 weeks. This one is called Rock Groups. He mentioned a puzzle series by John Tierney, and the one posted today reminds me of a problem I've posed in my Math for Elementary Teachers course - but this one's got a better storyline.
Sol, at Wild About Math, asked for help solving a problem his brother heard on the radio:
Bob and Alice are both millionaires. They’re both curious to know who is richer but they don’t want to tell the other one how much money they have. Without engaging a trusted third party, how can they both know who is richer?
I have played with a similar problem that I think goes like this:
10 mathematicians are out to dinner, and want to know their average salary. Without anyone finding out anyone else’s salary, how can they do this?
I remember that I saw the solution and liked it. (I may have solved it myself, even, but I'm stumped again now - the delights of a bad memory...)
Sol wants the answer. I'd prefer hints, myself.