Mystery puzzles

Peter R. Olpe

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Mar 9, 1986, 2:18:54 PM3/9/86

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When I was in college I used to play a sort of 'mystery' puzzle
that goes like this: The 'narrator' gives a one or two sentence
description of a situation, and then the 'players' have to guess
the mystery by asking the narrator 'yes' or 'no' questions. (That is,
the narrator can only answer 'yes' or 'no'.)

A typical mystery is:

'A man was found dead in a desert, with no water, and wearing a backpack.'

And the questions might go something like:

Q: Did he die because he ran out of water? (no)
Q: Is there anything around him but sand? (no)
Q: Did he ride a camel to where he is? (no)
Q: Did he walk there? (no)
Q: Hmmm... Was there any footprints around? (no)
Q: Does the backpack have something in it? (yes)
Q: .......

The answer is that the guy jumped out of a plane and his parachute
(the backpack) failed to open. This particular mystery is one of the
easier ones, partly because there are a lot of clues in the opening
statement.

Other puzzles include:
'A man stopped in front of a hotel and realized he was bankrupt.'
'The music stopped and the man died.'
'A man turned on his car radio, then shot himself.'
'A man asked a bartender for a drink. The bartender pulled a gun on
him, then the man said 'thank you' and left.'

These are a lot of fun to play, both for the people trying to guess the
answer and for the 'narrator'. The questions are often very hard to
answer, even though they are yes-or-no answers, and the players often
go out on some tangent that leads them to very bizarre situations/solutions.
It is more fun with a lot of people asking questions, but if a player
guesses the answer he/she should drop out of the game so that the
rest of the players can continue.

The game often lasts 5-10 minutes per mystery, depending on the number
of people asking questions. The problem is that once the mystery
is solved the players usually ask for another one.

I have a list of about 20 mysteries, with their solutions. What I
am really interested in is NEW mysteries that I can add to my list.
If anybody knows of any of these puzzles, I would
greatly appreciate them sending me the mystery/solution. If anyone
would like a copy of my list, I would be more than happy to send it
to them. Thanks.
--
...ucbvax!\ -Pete Olpe-
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Alastair Foreman

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Mar 13, 1986, 6:20:30 PM3/13/86

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Here is an interesting puzzle, which I must confess I already know the
answer to, but would like to know the ELEGANT solution. I will post a
summary if there is sufficient response.

Puzzle:

Take a half a cup of tea, and a half a cup of coffee.
Take one tablespoon of the tea and mix it in with the coffee.
Take one tablespoon of the mixture and mix it back in with the tea.

The question is, which of the two cups (if either) contains more of
its original contents, and WHY.

Remember, I'm looking for simple, elegant solutions here....

enjoy

--
Alastair Foreman
New Media Technologies Ltd.
..decvax!microsoft!ubc-vision!winston!foreman
..ihnp4!alberta!ubc-vision!winston!foreman

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Burnaby, B.C., Canada,
V5C 5T5
(604) 291-7111

Fai Lau

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Mar 19, 1986, 8:31:54 AM3/19/86

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>
> Here is an interesting puzzle, which I must confess I already know the
> answer to, but would like to know the ELEGANT solution. I will post a
> summary if there is sufficient response.
>
> Puzzle:
>
> Take a half a cup of tea, and a half a cup of coffee.
> Take one tablespoon of the tea and mix it in with the coffee.
> Take one tablespoon of the mixture and mix it back in with the tea.
>
> The question is, which of the two cups (if either) contains more of
> its original contents, and WHY.
>
> Remember, I'm looking for simple, elegant solutions here....
>

The answer is neither one. Since the resulted volumns of both
liquids haven't changed, and they are equal to begin with, whatever
amount of original liquid one container loses must be replaced by
the same amount of liquid which are originally found in the other
container. So it follows that the other container loses the exact same
amount of its original liquid. And the solution goes that the two
containers eventually not only have the same amount of their original
liquids, but the same amount of foreign liquids as well.

Mitchell Marks

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Mar 19, 1986, 4:55:52 PM3/19/86

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In article <1...@winston.UUCP> for...@winston.UUCP (Alastair Foreman) writes:
>
>Here is an interesting puzzle, which I must confess I already know the
>answer to, but would like to know the ELEGANT solution. I will post a
>summary if there is sufficient response.
>
>Puzzle:
>
> Take a half a cup of tea, and a half a cup of coffee.
> Take one tablespoon of the tea and mix it in with the coffee.
> Take one tablespoon of the mixture and mix it back in with the tea.
>
> The question is, which of the two cups (if either) contains more of
> its original contents, and WHY.
>
>Remember, I'm looking for simple, elegant solutions here....
>
>enjoy
>
>--

If the amounts transferred are exactly equal, so that each container
ends up with its original volume, then the amount of coffee in the tea
and the amount of tea in the coffee have to be the same (or, as A.F.
poses the question, the amount of coffee left in the cup that was originally
pure coffee, and the amount of tea left in the cup that was originally
pure tea, are the same.)

Since coffee and tea aren't pure substances, and this should be a puzzle
about logic, not physical chemistry and the geometry of molecules, let's
make this two urns that start out with all red marbles in one and all
blue marbles in the other.

What you *don't* want to do is start asking how well it's stirred, and get
into probabilities. The answer is independent of how well you stir.

So we start out with R red marbles and B blue marbles in separate urns,
(they can be different, it doesn't affect the answer); we transfer X
red marbles into the blue urn, stir perhaps well or perhaps not, and transfer
X marbles of the mixture back to the red urn.

Now the red urn has R-X+X = R total marbles again. A certain number of them,
Y, are blue, 0 <= Y <= X. So the red urn still has R-Y red marbles. It
is missing Y of the original R red marbles. These red marbles have to be
over in the blue urn; and they are the only red marbles in the blue urn.
So the blue urn has B-Y blue marbles left. Each urn has Y marbles of the
non-original color, and [original number] - Y of the original color
marbles. And this holds regardless of the exact value of Y.

We would bring in probability and discuss stirring only if we wanted to
estimate Y -- but we don't need Y.
--

-- Mitch Marks @ UChicago
...ihnp4!gargoyle!sphinx!mmar

bri...@inmet.uucp

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Mar 19, 1986, 5:34:00 PM3/19/86

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McCooey David I

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Mar 20, 1986, 10:57:44 AM3/20/86

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> Puzzle:
>
> Take a half a cup of tea, and a half a cup of coffee.
> Take one tablespoon of the tea and mix it in with the coffee.
> Take one tablespoon of the mixture and mix it back in with the tea.
>
> The question is, which of the two cups (if either) contains more of
> its original contents, and WHY.
>
> Remember, I'm looking for simple, elegant solutions here....
>
> enjoy

Solution: (The cups contain EQUAL amounts of their original contents.)

We begin with equal amounts of coffee and tea, right?

We end up with a half cup of liquid in each cup, right?
(this is the key...)

The cups must therefore contain the SAME amount of their
original contents, RIGHT?

If, say, the tea cup ends up with more tea in it than the amount
of coffee in the coffee cup, then there must be less coffee in
the tea cup than the amount of tea in the coffee cup (because
each cup ends up with the SAME amount of liquid).
But this means that there is more tea (total) than coffee (total),
which is impossible:

| | | |
|_______________| This |_______________|
| COFFEE | situation | |
|_______________| is | TEA |
| | impossible |_______________|
| | because | |
| | there | |
| TEA | is | COFFEE |
| | more | |
| | tea | |
|_______________| |_______________|
TEA CUP COFFEE CUP

The nice thing about this problem is that it doesn't even matter
how (badly) the tea is mixed in with the coffee, as long as the
same amount of liquid is returned to the tea cup.

Dave McCooey
AT&T Bell Labs, Whippany
ihnp4!whuxlk!dim

twb

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Mar 21, 1986, 9:19:48 AM3/21/86

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> Puzzle:
>
> Take a half a cup of tea, and a half a cup of coffee.
> Take one tablespoon of the tea and mix it in with the coffee.
> Take one tablespoon of the mixture and mix it back in with the tea.
>
> The question is, which of the two cups (if either) contains more of
> its original contents, and WHY.
>
> Remember, I'm looking for simple, elegant solutions here....
>

1. T represents Tea, C represents Coffee
2. Start with 8 tbl(=1/2cup) of each. 8T 8C
3. Coffee get 1T 7T 8C+1T
4. 1 tbl of the C mixture
is 1/9T+8/9C
5. Put that into the T cup 7 1/9T+ 8/9C 7 1/9C+ 8/9T
6. Each cup has 7 1/9 tbl of the original contents and 8/9 tbl of
the other liquid.
QED
Tom.