test your intelligence 2
i personally feel this is a gd and challenging question...
You have 12 coins. One of them is "defective", meaning that it weighs differently from the others. How do you tell, using a balance, which coin is defective, and whether it is lighter or heavier than the others, in 3 weighings?
have i asked this before?
You have 12 coins. One of them is "defective", meaning that it weighs differently from the others. How do you tell, using a balance, which coin is defective, and whether it is lighter or heavier than the others, in 3 weighings?
have i asked this before?
posted by cLeMeNt at 8:06 PM
13 Comments:
i still thinking bout it.
have a couple of solutions which always leave me till the last grp of balls.
but jus to let u noe tat some1 is thinking bout ur post...
but will still try solving nevertheless!
wait fer my news
let me try...
1st weigh:6 on each side of balance
2nd weigh:3 of the heavier 6 on each side of balance
3rd and last weigh:any 2 of the heavier 3...
from there, if the 2 balance, the odd one is the heavy one. if one is heavier, then obviously is that one.
let me try...
1st weigh:6 on each side of balance
2nd weigh:3 of the heavier 6 on each side of balance
3rd and last weigh:any 2 of the heavier 3...
from there, if the 2 balance, the odd one is the heavy one. if one is heavier, then obviously is that one.
hi anonymous,
err.. ur ans is wrong. cos the qn states that the defective coin weighs DIFFERENTLY from the rest. hence, u do not know whether it is heavier or lighter.
cHeeRs
sorry i din read carefullyso what's the answer?
i m going to give the most stupid ans.
i know it violates the rules la, but i just cant think of an answer and i will just throw this one in.
i m just playing with english.
put 6 on each side, den remove one from both sides until it balances.
the 2 coins that were removed to cause this balance r the suspects.
den take one of the suspect weigh against those non suspects. if it doesnt balance, den see the result n conclude
if the suspect balance wif the non suspect, den just take the other coin n weigh against the normal coin and will see the result.
i know the step 1 weighing sucks la, but i just try my luck, and too lazy to think anymore.
ya.. gekleng, nice try but i'm afraid it's wrong.
sorry that i won't disclose the ans on my blog cos i scared it means 'destroying' another gd qn.
but in case, u really want to know, to drop me ur email, and i shall reply
balance 4 on each side.
scenario 1: balance
this is easy then. means the 4 tat is not weighed has the unbalance coin. take 3 of that 4 n weigh with 3 of the balance one. now u know the unbalance coin is either heavier or lighter, if not, then the last coin is the unbalance one and u can use the last weigh to find tat out.
scenario 2: not balance
now there is the lighter side and the heavier side. take the 4 from the lighter side n change with the 4 standard coins. take 1 from the heavier side n put with the 4 standard coins. so now the heavier side got only 3, and the other side 5. so, take 2 coins from the lighter set of 4 and put them into the heavier side. now if the heavier side is still heavier, then the 3 original inside has the unbalance coin. if now the heavier side is lighter, then the 2 added in coins has the coin. if the other side is heavier, u got the coin already. if it is balance, the coin is in the other 2 coins not in the balance now. the third weigh will help u find tat coin.
*note: the idea is to get either 2 or 3 coins at the last weigh, and u have to know whether it is heavier or lighter. at first weight i only manage to either eliminate 4 or 8 coins. in the 8 case, i split the coins into sets of 1-3-2-2, if u can see what i mean.
how? u still dun understand ah? LoL
well done!!! jonnie.. keep it up.. stay tuned next week
if the heavier side is lighter? isn't it the same as the other side being heavier?
think should be take 3 standard ones plus one from heavier side to weigh with 3 from the heavier side plus one from the lighter side. i got this from jonnie's answer. am i right?
Anonymous said...
if the heavier side is lighter? isn't it the same as the other side being heavier?
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yalah. so if the other side being heavier, so the one added from the originally heavier side is the coin lo.
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Anonymous said...
think should be take 3 standard ones plus one from heavier side to weigh with 3 from the heavier side plus one from the lighter side. i got this from jonnie's answer. am i right?
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ya i think lidat also can. the idea is to split the lighter 4 and the heavier 4 into max sets of 3 so tat last weigh we can find the coin.
i hope everyone's enjoying themselves with the qns posted and this discussion that had been generated
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