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The mkiv Supra Owners Club

Another riddle


Ewen

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Same vein as Gaz's thread recently......

 

You are in a treasure vault. There are three large sacks in front of you, and a weighing scale that operates with a ten pence piece. One sack contains genuine gold coins. Two sacks contain fake gold coins that visually, are impossible to tell apart from the genuine ones. You are allowed to choose and keep the contents of one sack, and to help you choose you are given a ten pence piece with which you can use the weighing scale once only. You are also told that although each sack weighs exactly the same, the genuine gold coins weigh 5% more than the fake ones.

What would you weigh to make sure you choose the right sack ?

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id pick up all 3 bags, jump on the scales look at the weight, drop one bag look at the scales and work out the difference. Drop the next bag work out the difference drop the last and work out the difference.

 

Whichever bag made the biggest difference is the bag id take. :)

 

:) Sorry, no. All three sacks (including contents) weigh exactly the same.

Also, to keep things simple, the scales dont work like that....they register one weight only.

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ive sussed it (i think). The coins look identical but if the genuine ones can weigh up to 5% more and all sacks weigh the same then one sack will be less full so id just take that.

 

the scales are a decoy...

 

how did i do :)

 

Yeah, just count the coins in each bag and the one with the fewest is the right one

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ive sussed it (i think). The coins look identical but if the genuine ones can weigh up to 5% more and all sacks weigh the same then one sack will be less full so id just take that.

 

the scales are a decoy...

 

how did i do :)

 

:) That would work, but when you open the sacks you find there are also some rocks in them too, of different sizes and weights. Foiled ! The generous benefactor smiles, and points toward the weighing scales......

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use the coin to scratch the coins , the real ones will remain the same , fake ones will have a different core material

 

For the sake of the challenge, the only difference between the genuine and fake gold coins is that the genuine ones weigh 5% more than the fake ones.

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Weigh two coins, one from each of 2 random bags.

 

If they weigh the same, take the other bag.

If one coin is heavier than the other, take the bag it came from.

 

:) getting closer, but the scales only work once....you can only weigh one item, or group of items together, once.

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You take one coin from the first bag, two coins from the second bag and three coins from the third bag and weigh them all up together. If you know the difference between the weight of a "fools coin" and a real coin and the weight of a real coin, the trick is done.

a=the weight of a real coin

b=the weight of a fake coin

 

You have weighed 6 coins. You are supposed to have 6 times a; but you don't. You have c (the weight of your six coins).

According to you the fake coins are heavier (that is unlikely, but anyway), so c is greater than "six times a". Subtract the latter from the former. Divide by "b-a" (ie. the difference between a and b). You either have one, which means the fakies were in the first bag, or two, which points a condemning finger to the second bag or three blah blah blah

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You take one coin from the first bag, two coins from the second bag and three coins from the third bag and weigh them all up together. If you know the difference between the weight of a "fools coin" and a real coin and the weight of a real coin, the trick is done.

a=the weight of a real coin

b=the weight of a fake coin

 

You have weighed 6 coins. You are supposed to have 6 times a; but you don't. You have c (the weight of your six coins).

According to you the fake coins are heavier (that is unlikely, but anyway), so c is greater than "six times a". Subtract the latter from the former. Divide by "b-a" (ie. the difference between a and b). You either have one, which means the fakies were in the first bag, or two, which points a condemning finger to the second bag or three blah blah blah

 

:) spot on

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