A rock hard puzzle for you all...

[ilovepiano]

You have twelve balls of identical size. They all way exactly the same, except for one. You have a set of scales (of the balance variety) which you can ONLY USE THREE TIMES.

Your task is to work out how to find the odd ball, and whether it is lighter or heavier than the other eleven.

Good luck.

[*alicia*]

hold 1 in each hand an if it feels heavier or lighter then weigh it an weight another 1 2 c if it the right 1

[ilovepiano]

Originally Posted by *alicia*

hold 1 in each hand an if it feels heavier or lighter then weigh it an weight another 1 2 c if it the right 1

lol, no. You have to use the scales. Just imagine the difference in weight is to small to tell by holding them.

[*alicia*]

awww i fort i was dead cleaver then thats well not far

[lippiatte]

i can only do it in 4 uses of the scale.

[italooldskool]

Get a long stick and some string, cut the string into two equal lengths, tie the string around each ball exacltly the same way, and connect one ball to each end of the stick. Hold the stick exactly in the middle with your thumb and forfinger, you have now created your own scale. The slightly heavier ball will obviously weigh down. You could do this with each ball, and get the results without using the official scales and walk off like a right smarmy twat lol

[grad]

that's a bit straight forward isn't it?

weigh 6 on each side, the heavier side has your ball in.

weigh those 6, 3 on each side, again your heavier side has the ball in.

that leaves you with 3 balls, weigh 2 of them, if one's heavier then that's your ball, if they balance then it's the one not on the scales.

that it?

erm just re read your question and it's not is it...dunno how you can tell if it's lighter or heavier than the rest mmm not as straight forward as i thought, in fact i can't see how that can be done if you don't know if the balls heavier or lighter from the start.

[grad]

gggrrr thought i had it then by splitting them into groups of 3 but at one point you need to use the scales 4 times..good one this.

[silocybe]

I know youve got to number the balls ! then put them into 3 groups,then its the process of elimination , balls 1,2,3,4 v 5,6,7,8 , but I cant remeber the elimination , it becomes complicated

[Biskit]

lol is this one ov them trick quesi's? The odd ball is a diffo colour

[ilovepiano]

Originally Posted by Biskit

lol is this one ov them trick quesi's? The odd ball is a diffo colour

pmsl Na mate, it's not a trick, and I promise you it can be done.

Silocybe, you're on the right track.

[dj_jam]

Number the balls like silocybe said 1, 2, 3, 4, 5 , 6 ,7 8, 9 10, 11, 12 (because u cant count??)

Start off with them in 3 groupsu were getting there grad) [1, 2, 3 and 4], [5, 6, 7 and 8] and [9,10,11 and 12]

Weigh 1, 2, 3 and 4 vs 5, 6, 7 and 8 with 3 possible outcomes:

1. If they balance then 9,10,11,12 have the odd ball, so weigh 6,7,8 vs 9,10,11 with 3 possible outcomes:
1a If 6,7,8 vs 9,10,11 balances, 12 is the odd ball. Weigh it against any other ball to determine if heavy or light.
1b If 9,10,11 is heavy then they contain a heavy ball. Weigh 9 vs 10, if balanced then 11 is the odd heavy ball, else the heavier of 9 or 10 is the odd heavy ball.
1b If 9,10,11 is light then they contain a light ball. Weigh 9 vs 10, if balanced then 11 is the odd light ball, else the lighter of 9 or 10 is the odd light ball.

2. If 5,6,7,8 is greater than
1,2,3,4 then either 5,6,7,8 contains a heavy ball or 1,2,3,4 contains a light ball so weigh 1,2,5 vs 3,6,12 with 3 possible outcomes:
2a If 1,2,5 vs 3,6,12 balances, then either 4 is the odd light ball or 7 or 8 is the odd heavy ball. Weigh 7 vs 8, if they balance then 4 is the odd light ball, or the heaviest of 7 vs 8 is the odd heavy ball.
2b If 3,6,12 is heavy then either 6 is the odd heavy ball or 1 or 2 is the odd light ball. Weigh 1 vs 2, if balanced then 6 is the odd heavy ball, or the lighest of 1 vs 2 is the odd light ball.
2c If 3,6,12 is light then either 3 is light or 5 is heavy. Weigh 3 against any other ball, if balanced then 5 is the odd heavy ball else 3 is the odd light ball.

3. If 1,2,3,4 is greater than 5,6,7,8 then either 1,2,3,4 contains a heavy ball or 5,6,7,8 contains a light ball so weigh 5,6,1 vs 7,2,12 with 3 possible outcomes:
3a If 5,6,1 vs 7,2,12 balances, then either 8 is the odd light ball or 3 or 4 is the odd heavy ball. Weigh 3 vs 4, if they balance then 8 is the odd light ball, or the heaviest of 3 vs 4 is the odd heavy ball.
3b If 7,2,12 is heavy then either 2 is the odd heavy ball or 5 or 6 is the odd light ball. Weigh 5 vs 6, if balanced then 2 is the odd heavy ball, or the lighest of 5 vs 6 is the odd light ball.
3c If 7,2,12 is light then either 7 is light or 1 is heavy. Weigh 7 against any other ball, if balanced then 1 is the odd heavy ball else 7 is the odd light ball.

BALLS

[ilovepiano]

Well done Jamiii, I hope you did it all without cheating!

[dj_jam]

Originally Posted by ilovepiano

Well done Jamiii, I hope you did it all without cheating!

took a while to remember how to do it...got told it in skool...... i may have looked for sum help...as when i try to explain shit.....it comes out shit lol......

it was in an electronics lesson???? took us months to work out...

[grad]

nice one...had me scratching my head did that one.