Numeracy Answer from Fall 2017

The Winning Response
Submitted by: Stephen Wyle (father of Alexandra Wyle Eastman CdeP 1986, Noah Wyle CdeP 1989, and Aaron Wyle CdeP 1993; and grandfather of Owen Wyle ’21). 

The answer is one ball.
I assume that each box is mislabeled.  Therefore, if I take a ball from the box labeled “BW” and the ball is black, then that box must have two black balls (since it can’t be one black and one white).  Therefore, the box labeled “WW” must have one white and one black ball since it cannot have two white balls, and we have already found the box with two black balls. The box marked “BB” must then have the two white balls.
The same logic would apply if the ball removed had been white.

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