a math riddle...

[VJ]

Well, I don't know the answer (yet ?), but I'm curious to your answers:

There are 12 balls, one of them is heavier or lighter than the others. You have a traditional scale and are only allowed to weigh 3 times.
You have to state which one is the "odd" ball, and whether it is lighter or heavier than the others. How do you do this ?

Jörg

[Wombat]

"traditional" scale? Is this a weight scale, or a counterbalance scale?

[Dogbert]

I solved it a few months ago

[VJ]

Originally posted by Wombat
"traditional" scale? Is this a weight scale, or a counterbalance scale?

Well, I'm not familiar with the English names, but the ones where you can put stuff on one side, and stuff on another side... (=counterbalance, right ?)


Jörg

[Pace]

Damn hard, just spend 15 minutes on it so far, nowhere near it. If I got lucky it would work, but I can't guarantee finding the ball, never mind whether it's heavier or lighter.

[GNEP]

I can do it with a bit of a "cheat" (2 different ways)

[J1NG]

Well, that solution is - more or less - easy to get, but that assumes that the rest of the balls are the same weight. What happens when they're not the same weight?

OK, had enough of maths for one day.

J1NG

[J1NG]

Hmmm, what's with the deleting recently?

Read some weird posts today...

Sorry, slight tangent there...

J1NG

[Dogbert]

SPOILER ALERT:

IIRC this is the answer:


? = unknown
H = potencialy Heavy
L = potentialy Light
V = Verified to be ok

Make 3 groups of 4

4? 4? 4?

weight 4 against 4.

Option 1: 4? = 4?

then you now have 8V and 4?

...............if 3V = 3?
..............................we now have 11V and 1?
..............................do 1V = 1? and get the answer.

...............if 3V != 3?
..............................3? becomes either 3L or 3H, we'll assume they are 3L
..............................if 1L = 1L the extra one is faulty
..............................if 1L != 1L the lighter one is the faulty one.


Option 2: 4? != 4?

We now have 4V 4H 4L

...............if 4V + 1H = 3H + 2L
..............................we now have 10V 1L 1H
..............................if 1V = 1L then 1H is the one
..............................if 1V != 1L then 1L is the one

...............if 4V+1H <(lighter than) 3H + 2L
..............................we now have 9V 3H
..............................if 1H = 1H the last one is faulty
..............................if 1H != 1H the heavier one is faulty

...............if 4V+1H >(heavier than) 3H + 2L
..............................we now have 9V 1H 2L
..............................if 1L = 1L then 1H is faulty
..............................if 1L != 1L then the lighter one is faulty.

[thop]

all balls are the same weight and it is a counterbalance scale. the solution is actually very easy and simple, but for the love of MURC i cant remember it and if i start thinking about the solution my head will explode.

[SpiralDragon]

well concerning math and balls;

1) 1+1 is toooooo complicated for me = 3

2) "i've got big balls, she's got big balls, but he's got the bigst balls of them all" now the only problem is i cant remeber who did this song... (AC/DC??)

[KRSESQ]

I hate logic puzzles!!!

Kevin

[agallag]

Yup, ACDC, from the "Dirty Deeds Done Dirt Cheap" album.

[Gurm]

My balls are very popular,
my ballroom's always full.

And everybody comes and comes again!

If your name is on the guestlist,
noone can take you higher.

Everybody says I've got
GREAT BALLS OF FIRE!

or perhaps...

My balls are always bouncing
to the left and to the right.

It's my belief that my big balls
should be held EVERY NIGHT!

- Gurm

[Strahd]

Some bals are held for charity
and some for fancy dress,
But when they're held for pleasure
there the balls that I like best.