Posts Tagged ‘Bayes’

The Faulty Die

Friday, August 24th, 2018

Jack was sitting at a café table reading a magazine when Jill sat down and ordered some pastries and a hot chocolate.

“What are you reading with such a puzzled look on your face,” said Jill, munching a delicious apple strudel with a flaky crust.

“It’s a puzzle about a guy who is given a bag with 100 dice and told that one of the dice is faulty since it has six dots marked on all of its faces,” said Jack. “Then he is told to reach into the bag and pick one die.”

“So what’s the puzzle all about, then?” asked Jill, taking a small sip of her hot chocolate.

“You’re supposed to work out how many sixes in a row the guy has to throw before he can be 90% sure that the die he is throwing is the faulty one,” said Jack.

“Hmm… since there are 100 dice, it seems to me that you’d have to throw an awful lot of sixes to be sure the die was faulty,” said Jill.

“Maybe,” said Jack, “but we have to give mathematical proof of the solution to the puzzle.”

“What’s the prize?” said Jill finishing off her apple strudel and taking a large sip of her not so hot chocolate.

“Jill, it’s ten thousand dollars for the correct answer,” said Jack.

“What are we waiting for, Jack!! Why don’t you get busy on figuring out the solution,” said Jill enthusiastically, “then we can rent an apartment in Mambo Bay for a great vacation.”

“Hmm…,” said Jack, “’Bay’ gives me an idea.”