# Thread: Probability question from a TV show

1. ## Probability question from a TV show

There are five boxes, one of which contains a prize. You choose one without opening it, and the probability for a win is 1/5. OK. Now you open one of the other boxes, and you find out that the prize is NOT in that box. Can you now say that the probability for you to win is 1/4?

The show is "Deal or no Deal" btw.

2. Originally Posted by changing_seasons
There are five boxes, one of which contains a prize. You choose one without opening it, and the probability for a win is 1/5. OK. Now you open one of the other boxes, and you find out that the prize is NOT in that box. Can you now say that the probability for you to win is 1/4?

The show is "Deal or no Deal" btw.
As long as that box was chosen at random, and not pre-selected to be one
without the prize. If the latter you have a variant of the Monte-Hall problem,
and the probability that the box you have contains the prize is still 1/5.

RonL

(A Bayesian analysis also gives the p=1/4 result confirming intuition,
but note 1 in 5 times the box opened will contain the prize)