Category Archives: probability

The birthday candle problem: solution

Recall the birthday candle problem I wrote about in a previous post: A birthday cake has lit candles. At each step you pick a number uniformly at random and blow out candles. If any candles remain lit, the process repeats … Continue reading

Posted in combinatorics, probability, solutions | Tagged , , , | 5 Comments

The birthday candle problem

After a 1.5-month epic journey1, I am finally settling into my new position at Hendrix College. Here’s a fun problem I just heard from my new colleage Mark Goadrich: A birthday cake has lit candles. At each step you pick … Continue reading

Posted in challenges, combinatorics, probability | Tagged , , , | 5 Comments

The mathematics of human knots

Have you ever played “human knot”? It seems to be a common icebreaker/team-building sort of exercise (just do a Google search for “human knot” and you’ll find quite a few pages discussing it). Everyone stands in a circle, then reaches … Continue reading

Posted in games, people, probability | Tagged , , , , , | 9 Comments

Change probabilities

Hello, dear reader! If you are a new reader, welcome! (I know there is at least one of you—thanks to commenter sg211 for prompting me to post again. =) I must apologize for dropping the ball on writing up the … Continue reading

Posted in challenges, counting, probability | 17 Comments

Challenge #7

This delightful problem is courtesy of Diana Davis (don’t follow the link unless you want to see the solution, though!), although I did take the liberty of formulating it slightly differently. =) One bright and sunny day, you’re walking down … Continue reading

Posted in challenges, geometry, probability | 7 Comments