Question 550086
Michael Phelps has 6 gold medals to place on an empty, three-shelf display case.  
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[I suppose near his bong collection <font face = "wingdings">J</font>!
About two years ago, Michael was photographed smoking weed in a bong 
here in my hometown of Columbia SC!
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The six medals are individual medals 1, 2, 3, and relay medals 4, 5, 6. The
three shelves of the display case are labeled A, B, C (top to bottom). Any of
the shelves may remain empty. The placement of the medals must obey the
following rules:

i) 4 & 6 may not be on the same shelf
ii) 1 must be on the shelf directly above the shelf 6 is on
iii) No shelf may hold all three individual medals
iv) Medal 5 may not be on shelf B

If medal 4 is on shelf B, what other medal must also be on the same shelf?
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We only need the first 2 clues. The last two are irrelevant.

If 4 is on B, then 6 is not on B by clue i)
So where is 6? Either A or C. But 6 can't be on A 
because clue ii) says 1 must be on the shelf above 6,
but there is no shelf above A. So 6 must be on C, and
by clue ii) 1 is above it on B.  So the answer is 1.

Edwin</pre>