Question 498405
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There are only three situations where Box 3 contains a yellow ball:


Case 1:  1:Y 2:R 3:Y,


Case 2:  1:R 2:Y 3:Y, or


Case 3: 1:R 2:R 3:Y


If it were case 1, Mary, knowing there are only two yellow balls and that she has seen both of them, knows immediately that box 2 must contain a red ball.


If it were case 2, Brandon would see two yellow balls in 2 and 3 and would know that Box 1 contained a red ball.


If it were case 3, Brandon, knowing that Mary was unable to tell by looking in 1 and 3 which color was in 2, knows that the ball in 1 could not be yellow.  Hence he would know that the ball in box 1 is red.


But none of these cases are true because neither Mary nor Brandon was able to name the color in the unseen box.  All other cases have a red ball in box 3, and so Ryan confidently stated.


John
*[tex \LARGE e^{i\pi} + 1 = 0]
My calculator said it, I believe it, that settles it
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