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to want some help to solve this puzzle

(6 Posts)
5Foot5 Mon 08-Nov-10 20:10:51

I am trying to compile a list of Christmas themed puzzles and trivia questions before Advent.

I came across this one the other day but then there was no solution:

"You have 25 Christmas ornaments of various shapes and sizes. All of these ornaments weigh the same except for one which is lighter. If you have a balance, how would you determine which Christmas ornament is the lighter one by weighing on the balance at most three times?"

Maybe it is me being thick but the best I can manage takes up to four times on the balance.

Can any bright sparks out there help?

Chil1234 Mon 08-Nov-10 20:24:00

Does this help at all Balance Puzzles?

Southwestwhippet Mon 08-Nov-10 20:24:08

Divide into two piles of 8 and one pile of nine.
First Weighing
Weigh the two 8s against each other to determine which of the three piles contains the lighter ornament.

If it is one of the 8 piles...
Second Weighing
Divide into two piles of 3 and one of two.
Weigh the two piles of 3 against each other to determine which of your three piles is the lighter.
third weighing
If it is the pile containing two ornaments you can just weight them against each other to determine

If it is one of the piles containing three ornaments weight two of them against each other to determine if one of them is lighter. If so, you have found the lighter ornament, if not, the lighter ornament is the one you did not weigh.

Obviously, if at the second weighing, it was the 9 ornament pile that contained the lighter ornament, they you can divide into three piles of three to determine which pile contains the lighter ornament and proceed as before.

Hope this makes sense, is really hard to describe but I just figured it out and thought would help!

5Foot5 Mon 08-Nov-10 20:32:34

Thanks both!!

I will include it in my list now I know it is solvable.

invisibleink Mon 08-Nov-10 21:14:20

OOH! Would love to see your list once it is finished!

InkyStamp Thu 02-Dec-10 21:28:17

Did you manage to compile 25? Can i steal them?

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