# Logic

Discussion in 'Just Talk' started by longboat, Nov 4, 2018.

1. ### longboatWell-Known Member

In front of you are 3 chests, labeled as shown:

You are told that all of the labels are incorrectly placed. Each label describes the contents of a different chest. To determine which chest contains 100 gold coins, you are allowed to pick a single random coin from a chest of your choice.

Which chest should you pick a coin from?

Note: The picking of a single coin is just a sample to figure out where the 100 gold coins are. The single coin is random, you don't get to look inside. Plus the chest you choose to pick the coin from does not, necessarily, need to be the chest of 100 gold coins. You're picking a chest first to determine which chest it is that has 100 gold coins in it.

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2. ### dobbieWell-Known Member

Does not matter which coin you get,you can then work out things by weight, after you weigh it.

3. ### longboatWell-Known Member

You can't weigh the chests.

B

5. ### Mike83Active Member

B can only contain 100 gold or 100 silver.

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6. ### dobbieWell-Known Member

You did not say that in the question.

7. ### Mike83Active Member

That then means A or C contain the 50/50 and 100 gold/silver

I'm still thinking........

8. ### gpierceActive Member

B Can't be mixed. So if you get a Gold coin, then B has the gold, A must be Silver, C must be mixed. If I get a silver out of B, then A must be mixed, C must be gold.

Assuming that the labels are reliably wrong, not possibly right.

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9. ### Mike83Active Member

B is either all gold or silver. As per incorrect label.
A can only be 50/50 or gold or silver. But not all gold as per incorrect label.
C can only be 50/50 or gold or silver. But not all silver as per incorrect label

So b is gold or silver
A is 50/50 or silver
C is 50/50 or gold.

So def open B

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10. ### kitfit1Well-Known Member

Yep............................me thinks that would be where i would be lifting the lid.

11. ### PhilSoActive Member

Brilliant.

Do another one

PhilSo

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12. ### PhilSoActive Member

You solved it...

You must have got distracted

PhilSo

13. ### Mike83Active Member

I thought I solved only the first step.
Then 10 mins later realised the first step was also the last step.

14. ### longboatWell-Known Member

You'll have to wait. I certainly ain't paying for it.

15. ### IsitreallyWell-Known Member

I'm not fussy, I'll happily take 100 Sliver coins. ☺☺

16. ### Harry StottleActive Member

Take a coin from the chest marked mixed because it must be all silver or all gold
If a gold coin comes out then that chest is all gold, if silver comes out then it's all silver.
If gold comes out then the chest labelled gold must be silver and the one labelled silver must be mixed
Conversely if silver comes out then the chest labelled silver must be gold and the one labelled gold must be mixed

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17. ### PhilSoActive Member

Two possible outcomes.

PhilSo (not)

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18. ### longboatWell-Known Member

Happily?
Gold has a SG of 19.3.
Silver is 10.5.
So, the chest full of gold coins weighs nearly twice as much as the one containing silver coins.
Then look at the spot price/g of gold compared to silver.
A ten year average for gold is about £28.
The ten year average for silver is about 60p
Let's say the 100 silver coins in the chest weighed in at 10Kg.
That means the 100 gold coins would weigh in at about 19Kg.
The 100 silver coins might be expected to be worth around the £6000 mark.
The 100 gold coins could be expected to have a value of around the £530,000 mark.

Still happy?

19. ### PhilSoActive Member

Not again Stan
This is tiresome.

20. ### Harry StottleActive Member

Here's one:
Charlie was driving to see his old friend in Tolchester but he hadn't been before and he had no map or satnav. He came to a tee junction with no signpost and didn't know whether to turn left or right. Two locals, Fred and Dave were standing talking on the corner, one was always truthful, the other never told the truth, but Charlie didn't know which was which.
What one question did he ask Dave so that the answer gave him the correct direction to turn?