Puzzle

[wings]

Seen as everyone is having so much fun on the maths quiz I thought I would post up another puzzle.

You are given 9 coins. 8 of them are the same weight, 1 is a different weight. Other than that the coins are exactly the same.

You have an old fashioned set of balances, like the Libra star sign. You are allowed only 3 turns at weighing the coins and may use nothing else as a comparison.

How do you find out which is the rouge coin and whether it is heavier or lighter than the other 8?

Winner gets a pint at Fed Cup

 

[Bambulus]

Remove one coin, and keep aside.

Split the remaining coins evenly for weighing (4 coins each side) and measure. There are two possible outcomes:

a) the two sides are evenly matched, in which case you have the lighter coin already set aside
b) one side is heavier

If b, then we continue by removing the heavier group of coins and setting aside. They're useless now.

Split the remaining coins in half and measure evenly again, two coins each side. Remove the heavier set of coins.

Split the two remaining coins evenly, and use the third chance of measuring to identify the lighter coin.


amirite?

 

[3L1TE hax]

Put 1,2,3,4 on one side, and 5,6,7,8 on the other leaving 9 off

if they balance, nine is a bad coin

if they dont; whichever is heavier (or lighter) you go (for example) 1 VS 3 leaving 2,4 off

if they balance go 2 vs 4 and one loses

if they dont balance one is wrong

EDIT: Goddamm.. even i nteh same minute

 

[Bon]

Seen as everyone is having so much fun on the maths quiz I thought I would post up another puzzle.

You are given 9 coins. 8 of them are the same weight, 1 is a different weight. Other than that the coins are exactly the same.

You have an old fashioned set of balances, like the Libra star sign. You are allowed only 3 turns at weighing the coins and may use nothing else as a comparison.

How do you find out which is the rouge coin and whether it is heavier or lighter than the other 8?

Winner gets a pint at Fed Cup

You call that a puzzle ?

 

[3L1TE hax]

Much simpler than two different theoretic and realistic answers IMO

 

[Bambulus]

EDIT: Goddamm.. even i nteh same minute

Aha

 

[Cook$]

Seen as everyone is having so much fun on the maths quiz I thought I would post up another puzzle.

You are given 9 coins. 8 of them are the same weight, 1 is a different weight. Other than that the coins are exactly the same.

You have an old fashioned set of balances, like the Libra star sign. You are allowed only 3 turns at weighing the coins and may use nothing else as a comparison.

How do you find out which is the rouge coin and whether it is heavier or lighter than the other 8?

Winner gets a pint at Fed Cup

The rouge coin will be the red one. Unless that's a typo and you meant rogue. In which case it'll be the one with the grey streaks in it's hair.

 

[wings]

Remove one coin, and keep aside.

Split the remaining coins evenly for weighing (4 coins each side) and measure. There are two possible outcomes:

a) the two sides are evenly matched, in which case you have the lighter coin already set aside
b) one side is heavier

If b, then we continue by removing the heavier group of coins and setting aside. They're useless now.

Split the remaining coins in half and measure evenly again, two coins each side. Remove the heavier set of coins.

Split the two remaining coins evenly, and use the third chance of measuring to identify the lighter coin.


amirite?

You have worked on the premise that it's lighter. It could be heavier.

Try again

 

[wings]

Put 1,2,3,4 on one side, and 5,6,7,8 on the other leaving 9 off

if they balance, nine is a bad coin

if they dont; whichever is heavier (or lighter) you go (for example) 1 VS 3 leaving 2,4 off

if they balance go 2 vs 4 and one loses

if they dont balance one is wrong

EDIT: Goddamm.. even i nteh same minute

If they don't balance how do you know which one is heavier and which one is lighter?

Try again

 

[tricky m]

split the coins into 3 groups weigh two groups if they balance disgard both sets fo coins.(if they don't balance haven't worked that out yet)

split the third set and weigh 2 coins if they balance place other coin on scale and weigh again will tell you which is the differant coin and if it heavier or not.

if second weigh doesn't balance still change one coin for the third coin and weigh again if they balance the rogue coin is the one taken off and from previous weigh can determine if it's heavier or not. if the result is the same rogue coin is still on scale and you will know if hevier or not.