Interesting Maths Ques.

[jd_n]

There r 12 identical coins. Of these 12, only one r fake (fake one may b lighter or heavier). Havin only a normal balancing scale, how u gonna find out which coin is the fake. Have to determine the fake within 3 attempts on the balancing scale.

[roidan]

http://mathforum.com/library/drmath/view/55618.html

[bubble_gum]

amaths c6 onli sia

[sjsheng]

i listen to this maths question before... but i forget lieo the ans.. maybe sometime someday i go ask my frenz again n post the answer here.. this question is very very chim!

[ozy]

Well, I have another 2 for all the logic gurus here:

1. I have 10 piles of coins all weighing 10g each coin. Except for one pile which weighs 11g. Please weigh with 1 weighing on a weighing machine to find out which pile.

Simple? try this one

2. I have 10 piles of coins and each pile may weigh 10g each coin or 11 g each coin. Please use 1 weigh on the machine to find out which piles are the 11g piles.

actually there is a last part to this series of question, but I cannot remember. Anyone can help?