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The book contains 26 puzzles/games, most of which invite the reader to compute a probability or number of permutations. Five of the 26 contain errors, either in the text or in the answer section. Some of the errors are obvious. For example, the author states that the first puzzle has a unique solution. Any bright eight year old (the book is "for kids ages 8 and up") will find four distinct solutions without breaking a sweat.
Other errors are more subtle. For example, the author discusses two approaches to solving the first puzzle. In the first he uses pure trial and error. In the second, he uses a depth first algorithm. He notes correctly that the second method is much faster than the first. However, judging from his explanation, the author does not appear to know that he used two radically different methods. He attributes the difference solely to his choice of starting points.
Still other errors are simply baffling. One of the games involves a race. The reader is to determine which contestant will win. The discussion in the answer section would make sense only if the two contestants were engaged in a tug of war, not a race. In the puzzle following that one, the answer section has two contradictory answers.
Add to those the puzzles that depend on unstated assumptions (some reasonable, at least one completely absurd), and you're going to have one frustrated kid.
Like all the books in the Mind Games series, Probability Games has considerable visual appeal. It is a shame that more care was not used on the contents.
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