Jump to content

For those who like a puzzle


ATTAK Z

Recommended Posts

https://www.pistonheads.com/gassing/topic.asp?h=0&f=&t=1717877

 

The difficult bit is that you don't know if it will be lighter or heavier

 

Split into 3 lots of 4 matches (A), (B), (C)

 

Put (A) on left, (B)  on right.  If A=B then discard B. If A<>B put B to one side and replace with C.  If A=C you know the different match is in B. If A<>C you know the different match is in A.  You also know if it is heavier or lighter based on the difference in weights you saw (you did write them down didn't you? :lol: )

 

Assuming the different match is heavier, now you have 4 matches and can split 2 on each side, pick the heavy side ans split that into 2 and voila.

 

Full disclosure: I didn't read the rest of the thread but it did take me a few minutes to work it out!

Edited by Toon Chris
Link to comment
Share on other sites

Yeah I had it all worked out, then realised I didn't know if the odd one heavier or lighter, and that threw it out the window. I was going to halve them, keep the heavier side. then 3 on a side, keep the heavier side. Then 1 on each side. If it balanced, the one not on the scale is the odd one. But if the odd one was lighter than the other 11, I'd still have 6 to sort and no scale to use...going to read the rest of the thread for the solution now :lol:

Link to comment
Share on other sites

54 minutes ago, glrnet said:

Original linky still now worky and "address" linky comes back here!! :blush:

Not sure what's going on Graham ... I've had this before ... also if I press return now 

 

it will take me back to further up the thread and I have to scroll down again to finish the post

 

WEIRD

before you ask I'm on a MacBook Pro and Safari

 

it just took me back to post 6

Link to comment
Share on other sites

I had some issues that included ballsing up the forum on my Mac using Safari a little while back immediately after a Safari update and my friendly IT crew could not figure it out, but took their advice to change to Firefox and the 'issues' disappeared.

 

Damn sure they push out these software updates to cure reported issues only to create new ones and happy to let users be the guinea pigs.

 

Link to comment
Share on other sites

19 hours ago, Toon Chris said:

https://www.pistonheads.com/gassing/topic.asp?h=0&f=&t=1717877

 

The difficult bit is that you don't know if it will be lighter or heavier

 

Split into 3 lots of 4 matches (A), (B), (C)

 

Put (A) on left, (B)  on right.  If A=B then discard B. If A<>B put B to one side and replace with C.  If A=C you know the different match is in B. If A<>C you know the different match is in A.  You also know if it is heavier or lighter based on the difference in weights you saw (you did write them down didn't you? :lol: )

 

Assuming the different match is heavier, now you have 4 matches and can split 2 on each side, pick the heavy side ans split that into 2 and voila.

 

Full disclosure: I didn't read the rest of the thread but it did take me a few minutes to work it out!

 

Just one more thing...

 

Say the odd one is A1 and heavier, then...

 

You weighed Group A & Group B = A was heavier.

You weighed Group A & Group C = A was heavier.

Disregard Groups B & C.

You split into A1 + A2 and weigh against A3 + A4 = A1 + A2 are heavier.

Disregard A3 + A4.

You now know it’s A1 or A2,  haven’t you used up all three of your weighs?

Link to comment
Share on other sites

With a bit of luck you could do it.

Weigh A and B, if both the same it has to be C.

 

Weigh C1 and C2, no matter what the result, note it and remove C2 and replace with C3. If C1 was heavier than C2 and is heavier than C3 also, then you know C1 is the odd one. If it was heavier than C1 but weighs the same as C3, then you know C2 is the odd one. If C1 and C2 weighed the same and so does C1 and C3 then you know C4 is odd. If C1 and C2 weighed the same and the result is different with C1 and C3 then you know C3 is odd.

You can substitute heavier for lighter in this method, it doesn't matter as after weighing C1 and C3 you'll know which.

 

Of course this all goes to @*!# if A and B weigh different in the beginning as we don't know if it's supposed to be heavier of lighter.

Link to comment
Share on other sites

1 hour ago, SuperStu said:

 

Just one more thing...

 

Say the odd one is A1 and heavier, then...

 

You weighed Group A & Group B = A was heavier.

You weighed Group A & Group C = A was heavier.

Disregard Groups B & C.

You split into A1 + A2 and weigh against A3 + A4 = A1 + A2 are heavier.

Disregard A3 + A4.

You now know it’s A1 or A2,  haven’t you used up all three of your weighs?

 

You are right. A is four matches and you have only one weigh left. My method leaves you with 2 matches but you don't know which is the dodgy one.  Damn.

 

 

Link to comment
Share on other sites

You can't blow the whistle without posting the answer! :lol:

 

I did think the key to this is weighing two groups of 5 and leaving 2 to one side, but I can't quite figure out how you then root out the individual from there, if you don't know if it's lighter or heavier. GODDAMMIT

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...