This one's not for kids. There are 12 coins. One of them is slightly heavier or lighter than the others. You have a classical balance with two pans (which only indicates which pan is heavier/lighter). You are allowed to weigh only three times. Can you find out the coin which is different, and also whether it's heavier or lighter?
source : http://ankit-mathur.blogspot.com/
2007-03-14 20:30:23 · 7 answers · asked by Ankit 2 in Science & Mathematics ➔ Other - Science
First, divide the 12 into 3 piles. Weigh 2 of them. The fake coin is in the lighter one, or, if they weigh the same, in the third pile. Divide the found pile into 2 piles á 2 ccoins. Weigh them. The coin is in the lighter. Weigh the two coins in it against each other, the fake coin is the lighter one.
2007-03-14 20:40:47 · answer #1 · answered by Rumtscho 3 · 2⤊ 0⤋
Divide into groups with three each
weight group 1 and 2
If they are equal, take group 1 and 3, If they are equal, take 1 each from group 4 and we can conclude which is the faulty coin, if one and 3 is not equal then take 2 coins from group 3 and it can be found out.
If they are not equal, again group 1 and 3, and proceed with the same direction.
But, I am unable to give u whether the coin is ligher or heavier
2007-03-14 21:15:10 · answer #2 · answered by tdrajagopal 6 · 0⤊ 0⤋
shop all the luggage in the Pan to get a hundred and ten gms of weight on the size.Now initiate removing each bag one via one...you will see the replace of analyzing decresed via 20 gms the 2d you eliminate the bag with pretend money, with the bag with favourite money the version may well be only 10 gms.
2016-11-25 21:14:02 · answer #3 · answered by ? 4 · 0⤊ 0⤋
Simple, 4 piles of 3 each, weigh any two, if even it the 6 left out, if the scale tips then it one of the ones on the scale, you take the tipped scale and divide it again in 3 and weigh 2, you find it by tipping or left out, if it the ones left out you weigh them and go to the scale tipping and divid the ones again and weigh 2, it either tips or on the table.
only used 3 weighing.
2007-03-21 15:25:39 · answer #4 · answered by allen w 7 · 0⤊ 0⤋
There are 10 coin making machines. 9 out of them make coins
2007-03-20 03:37:02 · answer #5 · answered by pa r 1 · 0⤊ 0⤋
frist divide coins into two groups contains 6 each.
next wait two groups by using balance.the group which contains heavy coin can go down.divide this group into two each contains 3 each.the group which contains heavy coin will go down.next we go this 3 coins.in we weight only two if they are equal 3rd is required if not one go down is heavier coin
2007-03-14 21:24:35 · answer #6 · answered by yellamallesh 1 · 1⤊ 0⤋
please see solution at:
http://puzzle.dse.nl/teasers/coin_weighing_us.html
2007-03-22 14:24:38 · answer #7 · answered by Glider_Guider 2 · 0⤊ 0⤋