Question

each of three identical jewelry boxes has two drawers. in each drawer of the first box there is a gold watch. in each drawer of the second box there is a silver watch. in one drawer of the third box there is a gold watch while in the other there is a silver watch. if we select a box at random, open one of the drawers and find it to contain a silver watch, what is the probability that the other drawer has the gold watch?

detailed solution please

Answer 1

Once you find the silver watch, you can eliminate the box with the two gold watches. So it is either the box with the two silver watches or the one with gold and silver, two possibilities = 1/2.