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Five identical sweatshirts are placed in a bag. A letter is stiched to the back of each shirt; two of the letters are L's and three are W's. Chris, Hugo and Mary each pull out a sweatshirt without looking at it and put it on. Chris can see Mary's and Hugo's and correctly deduces, "I cannot tell which letter I have on." Mary's only see's Hugo's shirt and draws the same valid conclusion. Hugo sees no-ones shirt but uses his logic and is able to tell which letter is on his back. How does Hugo do it? Write a valid arguement that involves Chris's deduction. Then using that conclusion write a second arguement to justify Hugo's claim. Using Venn diagrams show your argument.

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So there are 5 sweatshirts, 2 with the letter L and 3 with the letter W. There are Chris, Mary and Hugo. Hugo finally can deduce what letter he has on his back. How?

1. Chris(=C.) sees Mary (=M.) and Hugo(=H.) and having correctly deduced C. cannot tell which letter he has. He could tell which letter he (Chris) has only if Mary and Hugo wore sweatshirts with the letter L. The explanation see ...

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