Michael Phelps has 6 gold medals to place on an empty, three-shelf display case.
[I suppose near his bong collection J!
About two years ago, Michael was photographed smoking weed in a bong
here in my hometown of Columbia SC!
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?
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