There's a weighing scale & 8 coins.7 r of the same weight,1 of them is heavier.U r  to weigh them only twice..
415329
Divide them into 2 groups: 6 and 2\nWeigh the group of 6 placing 3 on each side.\nIf they are equal, then the odd coin is in the group of two.  Weigh each coin to determine the heavier one.\nIf they are not equal, then take the 3 coins from the heavy side.\nTake two of them and place one on each side.\nIf they are equal then the third coin is the heavy one.\nIf they are unequal, then you know which one is heavier.
719127
Well you got a quarter and a nickel.  Because one of the coins is not a nickel, it is a quarter.  So the other one is a nickel.  Hehehe.... Good one.
992472
there are 2.2 pounds per kilogram.
581911
You only need to perform ONE weighing.\n\nFirst: take 1 match from the first box, 2 matches from the 2nd box, 3 matches from the 3rd box, ..., and 10 matches from the last box.\n\nWeigh the 55 selected matches. If the matches are all 10 grams, the total weight will be 550 grams. However, this is not true because some of them weigh 9 grams. For each 9-gram match, the total weight will go down by 1 gram.\n\nSo if the total weight is 549 grams, then the first box has the 9-gram matches.\n\nIf the total weight is 548 grams, then the 2nd box has the 9-gram matches.\n\n...\n\nIf the total weight is 540 grams, then the 10th box has the 9-gram matches.\n\nThus: Given this setup, the nth box has the 9-gram matches where n = (550g - total weight)
179072
the answers is more complicated that 1, or 40, its asking for four different numbers.  He can put stones on easch side of the scale, so addition of weights as well as subtration can be used.  For example the weights x = 1, y = 3, z = 9, w = 27 you can get many weights.\n1 = [x], 2 = [y-x], 3 = [y], 4 = [x+y],  5 = [z-y-x], 6 = [z-y], 7 = [x+z-y], etc. 34 = [x+z+w-y], 35 = [y+w-x], 36 = [y+w], 37 = [x+z+w], 38 = [y+z+w-x], 39 = [y+z+w] 40 = [x+y+z+w]\n\ni have to go watch hustle and flow, but thats the idea
1021893
Weight of US coins:  \n\nPenny Standard weight 2.5 grams\nNickel Standard weight 5.0 grams\nDime Standard weight 2.268 grams\nQuarter Standard weight 5.670 grams\n\nSo, you would only need 1/5 of a nickel to weigh a gram.
726629
Here's one...\n\nI have 30 cent in my hand.  One coin is not a quarter.  What are the two coins?\n\nAnswer: a quarter and a nickel.  JUST one coin in not a quarter.  NOT BOTH coins!\n\nI hope that works for you!\n\nIf not, here's another one...\n\nWhich one is correct:\nThe yolk are white.  OR The yolk is white.\n\nAnswer: NEITHER.  The yolk is YELLOW!\n\nI hope I was of some help!
408806
A quarter ( not a nickel ) and a nickel
113050
good question - took me a few minutes, so check if i'm right:\n\nA,B,C,D,E,F,G,H,I are the nine balls.\n\nweigh three v.s. three (A,B,C v.s. D,E,F)\n\nif scale is equal, then all six wieigh the same; now weigh G v.s. H\nif scale is still equal, then I is the heavier one.\nif scale tilts towards one side, say G, then the heavier is G. (same thing here for H)\n\nif first scale attempt is not equal, say the A,B,C side is heavier, then weigh A v.s. B (since one of the three here is the heavier one)\nif scale is equal, then C is heavier.\nif scale tilts towards one side, say A, then A is heavier. (same here for B)\n\nif first scale attempt is not equal and is heavier on the D,E,F side, simply repeat what i said in the previous paragraph, but with those balls.\n\nam i correct? :)
113666
You can type in a good description of the coin, it's likely that someone out there has another one just like it.  Otherwise, take it to a coin shop.
165094
First: 6 coins on one side, 6 coins on the other.\nResult: Whatever side is heaviest has the fake coin.\n\nSecond: 3 coins on one side, 3 coins on the other, from the pile that was heaviest in step one.\nResult: Again, the side that is heaviest has the fake one.\n\nThird: Take any two coins of the three you have left and weigh them. \nResult: If they are exactly the same weight then the one you have NOT wieghed is the fake. If one side is heavier than the other then that one is the fake.\n\nHope that was clear enough.
119352
All is clear once you understand the difference between mass and weight.\n\nIf you are not sure, look here:
1124992
Dimes:\n\n2268 grams  79.8336 ounces  4.9896 pounds\n\nQuarters:\n\n2268 grams  79.8336 ounces  4.9896 pounds\n\nIn other words, exactly the same.
474729
That the coin is dropped directly on it's side, there is no wind, and both sides of the coin are perfectly equally weighted.\n\nHowever, due to chaos, just dropping the coin from any reasonable height will net an equal division over a large enough sampling of tests.
56773
3 on one side, 3 on the other.\n\nIF they all balance, then the 2 left over has the lighter stone, just weigh and find out the lighter stone.\n\nIF they do NOT balance, then take the 3 that's lighter, take TWO stones from that group and weigh.\n\nIF they are balanced, the remaining stone from the 3 is the lighter stone.\n\nIf there's one that's lighter, then that's the stone you want.\n\nOnly two weighings in either case!
120720
you can use these numbers 1, 3 , 9 , 27\nactually these numbers are 3^0, 3^1, 3^2, 3^3 \nand here you are using 3 sounting system \nSo three counting system can use 0 , 1, 2 of each weight\nbut since we don't have except one weight of each unit, mathematics allow to use weights -1 , 0, 1 instead of 0, 1 ,2 so you can either put the weight unit with the weighed object (-1) or on the other side (1) or don't put it at all (0)\nBest Regards
342721
Depending on condition of the coins, the penny could be worth up to $8 and the nickel up to $2! Sorry!