You have 10 bags. Each bag has 10 coins. One of the ten bags is full of counterfit coins, but you don't know which bag. Real coins weigh 10 grams and counterfit coins weigh 9 grams. If you can use a scale only one time how can you determine which bag has the counterfit coins? You may only weigh it one time, meaning you can only read the scale once. You can't lift up the bags and feel which is heavier either. There is a logical solution.
First to get it right gets the 10 points!
If you get stumped then just email me and i'll send you the answer.
Have fun!
2006-09-27 10:40:57 · 10 answers · asked by Mariko 4 in Science & Mathematics ➔ Mathematics
Great you got it.
SmartyTarty: Where did you get marbles from? You must have been cheating.
2006-09-27 10:53:54 · update #1
Pull 1 coin from bag #1
Add 2 coins from bag #2
Add 3 coins from bag #3
etc.
Add 10 coins from bag #10
This is a total of 55 coins.
Now weigh them. If they were all real, you'd expect this to weigh 550 grams (55 x 10 grams = 550 grams). But instead it will be light.
If it is 1 gram light (549 grams), then the offending bag is #1.
If it is 2 grams light (548 grams), then the offending bag is #2.
etc.
If it is 10 grams light (540 grams), then the offending bag is #10.
The important things are that you must know that the counterfeit coins are lighter by 1g, and that the scale gives a reading (rather than being a balance scale). Thus is one weighing you can find the bag containing counterfeit coins.
2006-09-27 10:45:03 · answer #1 · answered by Puzzling 7 · 2⤊ 0⤋
Place the bags in a row. Take one marble from the first bag, two from the second bag and so on. Use the scales to weigh all the marbles you have taken from the bags. If the number of grams ends in 9, it is the first bag with 9 gram marbles. The total for the other bags will end in 0 since 10s are being added. The single 9 shows up as the rightmost digit in the sum of all the weights. If the number of grams ends in 8, it is the second bag with the 9 gram marbles because 2 times 9 equals 18 and that will be added to the total producing a number ending in 8. A rightmost 7 means it is the third bag with the 9 gram marbles. In each case the rightmost digit reveals which bag contains the 9 gram marbles.
Or:
Put all 55 marbles that you selected from the bags together on the balance. The number of grams that the total weight of these 55 marbles differs from 550 grams, is equal to the number of marbles of 9 grams that are among those 55 marbles, and that is equal to the number of the bag which contains only marbles of 9 grams.
2006-09-27 10:46:06 · answer #2 · answered by no such user 4 · 0⤊ 1⤋
Take one coin from the first bag, two from the second, etc. You will end up with 55 coins, that should weigh 550 grams. Weigh the 55 coins, and subtract that number from 550. That number will give you the counterfit bag. ie 550-545=5, the fifth bag is counterfit.
2006-09-27 11:29:38 · answer #3 · answered by ann_tracks 2 · 0⤊ 0⤋
Weigh one coin from the first bag, two from the second, three from the third, etc., all the way to ten from the tenth bag.
If all the coins were geniune, this would weigh 550 grams. However many ounces you're short is the number of counterfeit coins you've put on the scale -- which is the number of the bag with the counterfeits in it.
And with that, I reach level 4. :-D
2006-09-27 10:46:58 · answer #4 · answered by Jay H 5 · 1⤊ 0⤋
1)Label the bags.
2)Put 1 coin from bag #1, 2 coins from bag #2...10 coins from bag #10 on the scale
3)Find the weight of these combined coins. Based on the weight, you know which bag is counterfeit.
2006-09-27 10:49:50 · answer #5 · answered by tedhyu 5 · 1⤊ 0⤋
number the bags from zero to nine. take one coin from bag 1, two from bag 2,etc., up to 9 coins from bag 9. divide the result by ten - the remainder will indicate the counterfeit bag: remainder 0 indicates bag zero, remainder 1 indicates bag 9 is counterfeit, 2 indicates bag 8, etc., up to remainder 9, which indicates bag 1 is counterfeit.
2006-09-27 10:50:56 · answer #6 · answered by No Mo 2 · 0⤊ 0⤋
it was on an episode of columbo; one of the mensa guys was the murderer and posed it to columbo ....
i believe his wife helped him solve it since she liked riddles according to peter falks columbo character
you take one coin from bag 1 , 2 coins from bag 2, 3 coins from bag 3 ...and so on if memory serves correctly, then you perform your weighing just once [all that is needed amazingly enough :)] and you can determine which bag it was
to tell you the truth .... i would have wasted a little time trying to solve that one...
2006-09-27 10:47:24 · answer #7 · answered by xkey 3 · 0⤊ 0⤋
Put all the bags on the scale then start taking them off one by one until you see that only 90 grams were deducted. . . .
i don't think that's right but anyways send me the answer.
2006-09-27 10:51:04 · answer #8 · answered by Trish H 3 · 0⤊ 1⤋
the position are you able to locate the superstar...on yahoo solutions it would nicely be at a particular bar........ on the bar with buttons for exciting, digital mail, keep. it shines so bright.........sure it shines to golden from time to time it really is extraordinary...........@#**$%^ ok, universal for some rhyme yet with a contact Poof! it somewhat is the position you're!........if i click the superstar, my call looks contained in the list...i'm there very correct framed....flow locate your superstar
2016-11-24 23:06:03 · answer #9 · answered by Anonymous · 0⤊ 0⤋
Put them all in one bag.
2006-09-27 10:50:42 · answer #10 · answered by someones sister 4 · 0⤊ 2⤋