# Really interesting puzzle - try it for sure!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

India
May 2, 2007 1:42pm CST
you have 10 boxes of marbles, each box containing 10 marbles. you have an electronic weighing machine, which reports the weight put on it. now, all the marbles in all the boxes are 10 grams each, but all the marbles of one particular box are 9 grams each. in one weighing, you need find the box which has 9 gram marbles. how is this possible?
2 responses
@uath13 (8204)
• United States
2 May 07
Not to difficult. You number the boxes 1-10 You then take a number of marbles equal to the number on the box ( except for the 10th ) and place them all on the scale. If all the marbles weighed the same the weight would be 450 grams & the 10 box would be the one your looking for. If the reading is less then 450 grams you subtract that amount from 450. That # would then be the number of the odd box.
1 person likes this
• India
2 May 07
good job! now try this - yu have 12 coins and a weighing balance, one coin is counterfeit and you do not know whether it is lighter or heavier than the others. how can you determine the counterfeit coin in 3 weighings
@uath13 (8204)
• United States
2 May 07
Would be easy if there were only 8 coins. This may take me a bit.
@uath13 (8204)
• United States
2 May 07
Blast, I can do it in 4 weighings not 3. I'm outa time though, whats the answer?
• India
24 Jun 07
you have already got the answer but still i would like more puzzels.