Solve the challenging riddle?

Question

You have 12 coins. Eleven are made of gold; one is counterfeit. You don’t know which one because they all look alike. Also, you don’t know if the fake coin is heavier or lighter than a real gold coin. All eleven gold coins weigh the same.

You have a classic balance scale: two pans suspended from a pole with the center point balanced on a post. The scale can compare the weight of an object or objects in the left pan (L) with an object or objects in the right pan (R ). The scale will tell you if pan L is equal, heavier or lighter than pan R.

You can use the scale only three times for weight measurements with the coins. Can you determine not only which coin is fake, but if it is heavier or lighter than the real gold coins? Or, is the task impossible with only three measurements?

Answer 1

A counterfeit coin is one composed either of a base metal instead of gold or silver, or one which has had its weight reduced by clipping.

Answer 2

1) Take two of the coins and put one on each side.

1.1) If the scale does not balance then one of those is fake. Remove the coin on the left and replace with a new coin.

1.1.a) If these two coins do not balance, then the one left from the last weigh in is the fake and you know whether it is lighter or heavier.

1.1.b) If these two balance then the one you removed is the fake and you know the weight.

1.2) If the two original coins balance then you know you have two real coins.  

2) By hand you compare one of the real coins with each of the remainder until you find one that feels different. Then you place them on the scale to check.

Or you can just bite into them all.  

Answer 3

well you said 11 are made of gold and there is 12, so imassuming that the 12 one is silver or nickel or a different color.otherwise it should start out, they all resemble gold.the rest of the riddle is just to confuse you!!

Answer 4

its possible.. Assuming that the counterfiet is going to be a differnt weight, all you have to do is..

1. on the first weigh, devide the 12coins into 6 each obviously whey will have different weight, next step you however really have to assume.

2. take the 6 coins which is heavier, then devide that into 3, if you got the right bunch. 3 coins will be heavier than the other.

3. take that heavier bunch, then pick two and wiegh it, if it has thesame weight, then both are real gold and the one left would be fake one.

-hmm, its really going to be impossible, i guess you nid to know if its heavier or lighter, or atleast get 4 chance to use the scale.

Answer 5

im not smart

Answer 6

huh idk

Answer 7

use 10 coins and put them 5 on L and 5 on R. if they r not even take 2 coins on L and 2 coins on R. and then take 1 the 2 coins that match and take the side that does not match how much the gold coins r suppose 2 weigh and then weigh them again the remaining one is the fake coin. say the fake coins were not in the first 5. then just weigh the 2 coins that werent weighed and weigh them 2 figure out the fake. same thing with the 2 on L and 2 on R

Answer 8

...I was gonna say that they're all fake, but hahaha...umm...

Sure. Put one gold coin on a balance thing, and one by one put the other eleven on the....ahhhh!!! DAMMIT! 3 times huh?

...*pensive* I started at 2:10 okay?

...if I figure it out I'll come back XP

Answer 9

6 coins in one 6 in the other

if they weigh the same the counterfeit coin weighs the same as the gold coins.

If L is heavier or lighter than R that means the coin is either lighter than the gold ones or heavier

The task is impossible because you don't have enough times to weigh to get down to the one coin. Hope i get est answer!!!

What most of you are wrong about is like kidos answer

"6 on one side and 6 on the other

the heavier take off

3 on one side and 3 on the other

heavier side take off

put 2 on 1 side and 1 on one side

the lighter one is the correct one"

You dont know if the coin is the same weight, heavier or lighter so that would have many flaws.

Answer 10

I would make my dinner in the pan, and bend all the coins and see which 11 can bend, and which one can't.

Answer 11

6 on one side and 6 on the other

the heavier take off

3 on one side and 3 on the other

heavier side take off

put 2 on 1 side and 1 on one side

the lighter one is the correct one

Answer 12

To make it easier to understand, I will say label them from 1 to 12

There are two scenarios when you starting to measure the first time.

Scenario #1

Measure #1 - put 1 to 4 on one side and 5 to 8 on the other

If they are the same take all out.  If not, see Scenario #2

Measure #2 - put 9,10,11 on one side and 1 to 3 on the other.

If they are still the same then 12 is the counterfeit, see Measure #3

If not, then either 9,10 or 11 is the counterfeit one and you can see if it is heavier or lighter too(since you already know that 1 to 3 are real, if the counterfeit is heavier, 9,10,11 will drop lower, or rise if lighter) - then see Measure #3-1



Measure #3 - put number 12 on one side, put any one onthe other.

Since you already know that 12 is counterfeit, wheter it is light or heavy you can tell by this 3rd measurement.  DONE

Measure #3-1 - Now that you know that one of 9,10 or 11 is counterfeit, you'd also know if it was light or heavy.  Last step is to put 9 on one side 10 on the other.  If they are the same then 11 is the counterfeit, light or heavy as you see from #2.

If 9 and 10 are different, then the one that is lighter or heavier(what ever you see in #2) is the counterfeit.

______________________________________...

Scenario #2

Do the same Measure #1 but you will see that they're not balanced.

What this tell you is that the remaining(9,10,11,12) are all real.

**Remember the side that rise and the side that drop.  Let's just say 1 to 4 is on  "A" pan and 5 to 8 is on "B" pan.  Note the position of these pan.

Measure #2 - A little tricky, but as follow.  On "A" side put 1,10,11,12 on "B" put 2,3,4,5

If they are the same then 6,7, or 8 is the counterfeit, and you'd know the weight from #1 as you have noted the "B" position.  See #3

If not, and the balance does not change side(meaning "A" and "B" are still in the same position), then 1 or 5 is the counterfeit.  See #3-1

If it did change side("A" and "B" are now switches position), then 2,3,4 one is counterfeit.  And from #1, when 2,3,4 were on the scale on side "A", you can now tell the weight difference.  See #3-2

Measure #3 - 6,7, or 8 you can tell from #1 if they were heavier or lighter(Noted side "B").  Put 6 on one side 7 on the other.  If same, 8 is counterfeit.

if not then since from #1 you know what the counterfeit weight(heavier or lighter), then you'd know which one between 6 or 7  is the counterfeit.

#3-1 - put 1 on one side and any of the real on the other.  If same, then 5 is counterfeit and as you noted before, you can also tell if it's heavier or lighter.

If not same, then 1 is counterfeit.  Tell the wight the same way.

#3-2 - same way as #3 but use 2 on one side and 3 on the other.

Tell the weight the same way.

Done

Answer 13

Place 5 coins on each pan.  If the weight is equal, it's one of the other 2 coins.  Place each of these coins on a pan.  One will be different.  Remove one of the coins, and place one of the coins from the firs measurement on the empty pan.  If both weights are equal, the coin you removed from the previous measurement is the fake coin.  If the weights are different, then the coin you left on the pan from the second measurement is fake.

This is one way, so it is possible.  And you could tell by this method if they fake coin weighed less or morre than the real ones.

Or you could just bite coins until you come to one your teeth don't leave marks in.  That would be the counterfeit.