Category Archives: Riddles

Cheerful Test Your Intuition (#45): Survey About Sisters and Brothers

Posted on October 2, 2020 by Gil Kalai

You survey many many school children and ask each one: Do you have more brothers than sisters? or more sisters than brothers? or the same number? Then you separate the boys’s answers from the girls’s answers Which of the following … Continue reading →

Posted in Combinatorics, Probability, Riddles, Statistics, Test your intuition | Tagged | 7 Comments

TYI38 Lior Kalai: Monty Hall Meets Survivor

Posted on March 18, 2019 by Gil Kalai

For breaking news, scroll down. Lior Kalai: Survivor Meets the Monty Hall Puzzle We start with the classical question and go on with a new version contributed by my son Lior. Update: A few brief comments on the original problem … Continue reading →

Posted in personal, Probability, Riddles, Test your intuition, Women in science | Tagged , , , | 3 Comments

In how many ways you can chose a committee of three students from a class of ten students?

Posted on July 19, 2011 by Gil Kalai

The renewed interest in this old post, reminded me of a more recent event: Question: In how many ways you can chose a committee of three students from a class of ten students? My expected answer: which is 120. Alternative … Continue reading →

Posted in Mathematics to the rescue, Riddles, Teaching | 1 Comment

The Ultimate Riddle

Posted on February 2, 2010 by Gil Kalai

 Click on the picture!

Posted in Riddles | Tagged | 15 Comments

The Mystery Beeping Riddle

Posted on March 3, 2009 by Gil Kalai

    We came back from the airport with our daughter who has just landed after a four-month trip to India. The car was making a strange beep every so often. Maybe it is an indicator signal that should have … Continue reading →

Posted in Mathematics to the rescue, Rationality, Riddles | 12 Comments

Solution

Posted on January 18, 2009 by Gil Kalai

The solution to the last riddle is:

Posted in Riddles | 4 Comments

A Riddle

Posted on January 15, 2009 by Gil Kalai

 What is this?    

Posted in Riddles | 13 Comments

Greg’s Dinosaurs Riddle

Posted on November 7, 2008 by Gil Kalai

The two-riddles post was a success, and while corresponding with Greg Kuperberg he had a riddle for me about dinosaurs, and he agreed I will share it with you. Right before the Chixculub asteroid hit the earth, there were a … Continue reading →

Posted in Riddles | Tagged , , | 6 Comments

Two Math Riddles

Posted on October 23, 2008 by Gil Kalai

Usually I am not particularly good at telling math riddles or solving them, and I was not planning on presenting math riddles here. But these days, when mathematical blogs break new ground and enter uncharted territories, let me make an exception and tell you … Continue reading →

Posted in Riddles | Tagged , | 19 Comments