[Guest]

A quiz master has 3 boxes, A, B and C. $10,000 is in one of the boxes, and only the quiz master knows where is it. The contestant chose A. The quiz master opens C and it turned out to be empty. The quiz master gave a chance for the contestant to change his choice. Should he change? What is the probability of winning if he change or don't?

Edited March 29, 2008 by leexinyi88

[grey cells]

A quiz master has 3 boxes, A, B and C. $10,000 is in one of the boxes, and only the quiz master knows where is it. The contestant chose A. The quiz master opens C and it turned out to be empty. The quiz master gave a chance for the contestant to change his choice. Should he change? What is the probability of winning if he change or don't?

Without going too deeply:

The probability of the contestant winning will remain 50% irrespective of which box he chooses . Because onle the quizmaster knows the location of $10000 , unless the quizmaster is a cheat .

And it can be more than 50% for box A , as I had recently read in RD that often a person's first guess is his best guess.

[rookie1ja]

leexinyi88, welcome to the Den

this is a classic puzzle, most recognizably called the Monty Hall problem ... it is already posted (including long discussion) here

btw, it is not 50%

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