Cut the Knot: Probability Riddles

"He who untied the Gordian knot would rule all of Asia"So goes the legend of the tricky knot of Gordius, king of Phrygia. Many had tried; many had failed, but Alexander the Great simply cut the knot with his sword. He went on to conquer most of Asia, eventually reaching as far east as Northern India.Cut the Knot is a book of probability riddles curated to challenge the mind and expand mathematical and logical thinking skills. First housed on cut-the-knot.org, these puzzles and their solutions represent the efforts of great minds around the world. Follow along as Alexander Bogomolny presents these selected riddles by topical progression. Try them for yourself before reading their solutions. Just like it was for Alexander the Great, the non-trivial, unexpected solution might be exactly the one you need.