Submit a question to our community and get an answer from real people.
Submit

A riddle.

See additional comments, good luck!

you are given eight coins & are told that one of them is counterfeit. the counterfeit one is slightly heavier than the other seven,otherwise the coins look identical. using a simple balance scale how can you determine which coin is counterfeit using the scale ONLY TWICE?

Report as

1)put two coins at once in each plate.if the scale isn't balanced,then one of the plates must be containing the counterfeit.
2)remove one coin from each plate.if the scale is balanced,then the counterfeit is in your hand.if the scale isn't balanced,the counterfeit is in the plate.
3)if the scale is balanced in the 1st attempt,then none of the four is counterfeit.remove all of them and place another set of 4 coins 2 in each plate.
4)repeat step two.
here,you will be using the scale in step 1 and step 3 only.

Helpful (3) Fun (1) Thanks for voting Comments (7)
Report as
Yes, we'll done, I will raise the bar next time.
Report as
what ?
Report as
I will make the riddle harder next time.
Report as
ok fine :)
Report as
Yes, you are a legends. I will raise the bar next time.
Report as
the one who's framed the question is a legend too :)
Report as
Thanks, probably too much spare time on my hands!!
Report as
Add a comment...

hmmm....... wait for a while i want to try it out my self.

Helpful Fun Thanks for voting Comments (0)
Report as
Add a comment...

You could put one coin in see how much the scale says it weighs then keep adding then coins one by one and finally you'll notice one coin went down by a little more, or you'd notice once you put the first coin down all the other coins weighed a little less. Then you've found the counterfeit coin. And I only used the scale once :)

Helpful (1) Fun Thanks for voting Comments (2)
Report as
No , you can only use the scales twice.
Report as
That makes no sense. I didn't take anything off the scale so I only used it once plus that isn't a rule in the riddle. Therefore I did it right anyways :)) besides that top answer is wrong she used it in step 2 also she just didn't count it for some reason.
Report as
Add a comment...

Riddles are fun = )
I don't know about you, What I would do is place one coin on at a time on each scale. And hope you got it the second time. Other than that there is no way to figure it out only twice if that is the rule. Because you use the scale each time you place a coin set upon the scale.
You could: Place four in each, then re-start with the set that is uneven even Placing each upon the scale at a time then get your answer. Inevitably you are using the scale more than twice.

Helpful (1) Fun Thanks for voting Comments (4)
Report as
Hi,

Answer is: First weigh 3 coins against 3 others. If the weights are equal weigh the tee remaining two against each other. The heavier one is the counterfeit. If one of the group of 3 is heavier, weigh two of those against each other. If one is heavier then that's the counterfeit. If there equal weight then the 3rd is the counterfeit!

Thank you for participating.


Report as
lol fun. Still find it weird wish I had a scale = )
Report as
You used the scale like a four times that's not even right learn the answer to your own riddle -___-
Report as
That was at sgran^^
Report as
Add a comment...
Do you have an answer?
Answer this question...
Did you mean?
Login or Join the Community to answer
Popular Searches