# Another puzzle of the night

Mapraputa Is

Leverager of our synergies

Sheriff

Sheriff

Posts: 10065

posted 13 years ago

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This is also pretty easy, but I do not like puzzles I have to spend hours working on

There are 9 coins and one of them is false - it weight less than rest. You have a balance. How to find false coin with only two balancings? (veterans of triangle counting and rope burning are not welcome )

There are 9 coins and one of them is false - it weight less than rest. You have a balance. How to find false coin with only two balancings? (veterans of triangle counting and rope burning are not welcome )

Dirk Schreckmann

Sheriff

Posts: 7023

posted 13 years ago

Test six coins - 3 on each side of the balance. If these two groups of three are balanced, then remove all coins and only consider the three unchecked coins; otherwise, consider the lighter group of coins weighed.

Considering these three coins, place one on each side of the balance. If these two coins are balanced, then the one remaining unweighed coin is the false coin; otherwise, the coin that proved lighter on the balance is the false coin.

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Test six coins - 3 on each side of the balance. If these two groups of three are balanced, then remove all coins and only consider the three unchecked coins; otherwise, consider the lighter group of coins weighed.

Considering these three coins, place one on each side of the balance. If these two coins are balanced, then the one remaining unweighed coin is the false coin; otherwise, the coin that proved lighter on the balance is the false coin.

Mapraputa Is

Leverager of our synergies

Sheriff

Sheriff

Posts: 10065

posted 13 years ago

- 0

Apparently people in this forum have significant experience with false coins. :roll: Kinda scaring...

Michael, you do not need to know the answer to whisper something in my ear

Michael, you do not need to know the answer to whisper something in my ear

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Dirk Schreckmann

Sheriff

Posts: 7023

posted 13 years ago

I recently returned from a trip to El Salvador. I brought back with me a handful of coins, that while worth only about 3 cents each, are reported to work in the local parking meters as quarters - I wouldn't know anything about that. And yes, they are lighter than quarters.

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Originally posted by Mapraputa Is:

Apparently people in this forum have significant experience with false coins.

I recently returned from a trip to El Salvador. I brought back with me a handful of coins, that while worth only about 3 cents each, are reported to work in the local parking meters as quarters - I wouldn't know anything about that. And yes, they are lighter than quarters.

posted 13 years ago

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bad dirk! didnt you know that money pays for your mayors champaigne, caviar and call girls?

[ April 29, 2002: Message edited by: Randall Twede ]

[ April 29, 2002: Message edited by: Randall Twede ]

SCJP

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posted 13 years ago

- 0

wow i figured this one out...it is easy

i still dont get the one about the hats...wait maybe i do.

i still dont get the one about the hats...wait maybe i do.

SCJP

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Sameer Jamal

Ranch Hand

Posts: 1870

posted 13 years ago

- 0

make the three stack of 3 coins each

1 1 1

1 1 1

1 1 1

weigh any two stacks

1 1

1 1

1 1

either both weighs equal or one of the stack weighs less

if both weighs equal then the wrong coin must be in the third stack

1

1

1

so take out one coin and weigth the rest of the

two so either of the coin which weighs less is the wrong one and if both are equal then the coin which you have taken out is the wrong one

if both does not weighs equal then the wrong coin must be in the stack that wighs less, take that stack which weighs less and

take out one coin and weigth the rest of the

two so either of the coin which weighs less is the wrong one and if both are equal then the coin which you have taken out is the wrong one

1 1 1

1 1 1

1 1 1

weigh any two stacks

1 1

1 1

1 1

either both weighs equal or one of the stack weighs less

if both weighs equal then the wrong coin must be in the third stack

1

1

1

so take out one coin and weigth the rest of the

two so either of the coin which weighs less is the wrong one and if both are equal then the coin which you have taken out is the wrong one

if both does not weighs equal then the wrong coin must be in the stack that wighs less, take that stack which weighs less and

take out one coin and weigth the rest of the

two so either of the coin which weighs less is the wrong one and if both are equal then the coin which you have taken out is the wrong one

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