Not sure if this question being posted, but find it quite interesting There are 10 packets of coins - each packet has 10 coins - the coins in all the bags weigh 10g EACH except one bag where all the 10 coins in the bag weigh only 9g each. - you can only weigh the coins one time, how do you find out which bag has the coins that weigh 9g each? ps: weigh one time meaning you could only weigh once and take one reading you can weigh anyhow you like
Collect 1 coin from bag 1, 2 coins from bag 2, 3 coins from bag 3 and so on till you collect 10 coins from bag 10. Weigh them once and you will be able to find the 9g coin bag.
Ahha.......i have been posted with this question before. I think what ahsen meant was using a WEIGHING BALANCE to identify the ABNORMAL bag with the LEAST NO. OF TRIES. 10 bags is really easy. You will need 3 tries. I shan't spoil by posting the answer. When you guys have solved this warm-up, it's time to figure out my question ^^ My question is the same, except that there are 12 bags instead of 10. The answer is still 3 tries. Sounds impossible? It took me hours to figure out.........so have fun
To clarify things and prevent misunderstanding, i think i shall re-phrase the question. Here it goes I have 12 coins. All of them look identical, but one of them has a different weight from the rest (it can be lighter or heavier, we don't know). Using a weighing balance, how do you find out which coin is the abnormal one, as well as conclude whether it's heavier or lighter, with only 3 tries on the weighing balance? Have fun. I swear it isn't easy _______________________ ==========^=========
Hi DivingBirdie, I believe you have misinterpret ahsen's question. As for yours, one solution have been found if I am lucky. Weigh 1, 2, 3, 4, coins against 5, 6, 7, and 8 coins; If balance, weigh any three coins above against 9, 10 and 11 coins; If balance, take any of the above coin and weigh against the 12th coin and you will be able to know the weight difference of the 12th coin. If there is a difference in the first weigh let others try as I am not ready to crack my head over it.
is it not clear? sorry then, i try to rephrase again... What i mean was, i have 10 BAGS of coins, EACH bag has 10 pieces of coins. I know that EVERY coin in the bag weighs 10g ecept for ONE bag which has 10 coins that each of them weigh only 9g. Meaning, 9 Bags with 10g coins, 1 bag with 9g coins... provided is a Weighing machine, the type which you put the weight on it and take the reading, not the balance type. you can only weigh the coins ONCE.. how do you find out which bag is the one containing all the 9g coins? do i made myself clear.. tha's the best i can do...sorry...
I think your question is very clear. As Solitaire said, Divingbirde confused your question with another question.
Another lucky attempt. Weigh 1, 2, 3, 4 coins against 5, 6, 7, and 8 coins; If balance, weigh any three coins above against 9, 10, and 11 coins; If imbalance, weigh any of the two coins from 9, 10 or 11 against each other; Eg. taking the 9 coin to weigh against the 11 coin; If 9 > 11... 11 is lighter or 9 is heavier depending on the second weigh 9 = 11... 10 is either lighter or heavier depending on the second weigh 9 < 11... then 9 is lighter or 11 is heavier depending on the second weigh.
LOL.........looks like i think too much..........sorry for misinterpreting your question and hijacking your thread lol...... Anyway, solitaire has cracked my question partially, that is, 4 against 4 on first try, and getting a balanced result. As the first clue, i'll announce that the first step is correct (4-4). The part solitaire hasn't solved is that when the first weigh of 4-4 yields an imbalanced reading.(One side heavier). So, start thinking about the second and third steps, (first step 4-4 imbalanced). It's very logical ^^ Have fun
Original Question I have 12 coins. All of them look identical, but one of them has a different weight from the rest (it can be lighter or heavier, we don't know). Using a weighing balance, how do you find out which coin is the abnormal one, as well as conclude whether it's heavier or lighter, with only 3 tries on the weighing balance? Have fun. I swear it isn't easy
