SOLUTION: Five identical sweatshirts are placed in a bag. A letter is stitched 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

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Question 1042455: Five identical sweatshirts are placed in a bag. A letter is stitched 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 shirt without looking at it and put it on. Chris can see Mary’s and Hugo’s shirts and correctly deduces, “I cannot tell which letter I have on.” Mary sees only Hugo’s shirt and draws the same valid conclusion. Hugo sees no one’s shirt but uses his logic and is able to tell which letter is on his back. How does Hugo do it? First write a valid argument that involves Chris’s deduction. Then using that conclusion, write a second argument to justify Hugo’s claim. Diagram your arguments.
Answer by ikleyn(52932)   (Show Source): You can put this solution on YOUR website!
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Five identical sweatshirts are placed in a bag.
A letter is stitched 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 shirt without looking at it and put it on.
Chris can see Mary’s and Hugo’s shirts and correctly deduces, “I cannot tell which letter I have on.”
Mary sees only Hugo’s shirt and draws the same valid conclusion.
Hugo sees no one’s shirt but uses his logic and is able to tell which letter is on his back.
How does Hugo do it? First write a valid argument that involves Chris’s deduction.
Then using that conclusion, write a second argument to justify Hugo’s claim. Diagram your arguments.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

One obvious step is that what Chris sees is not "two Ls".

But there is no other arguments to move forward.

I think that the condition is inaccurate.

It is inaccurate in two points (at least). 

1.  The condition should include some communication between participants, 
    some exchange by messages.

    It is not described in the condition.


2.  "Mary sees only Hugo’s shirt and draws the same valid conclusion."

    Which exactly conclusion does Mary draw? It is ambiguous in this case.
    From the context, she can deduce 
         "I cannot tell which letter I have on.”  OR  
         "I cannot tell which letter Chris has on.” 

    From the other side, it doesn't matter which exactly conclusion Mary deduces, because she has no enough info to make any valuable conclusion.

Any comments ?


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