Simple Logic Problem

[rfr3sh]

put all 3 on the scale...and remove bags till you know which is the right one

[Seaweed]

Im stumped

[CamNewtonOutfit]

This is a relatively easy problem, so maybe the geniuses can refrain from answering right away (PM me if you know the answer Ganch, Data, Justin, Donjuan, etc...). For everyone else:

You have 3 bags of coins with an unknown # of coins in each. 2 of the bags are fake (fool's gold), while 1 bag has real gold coins. The coins are identical except that the real gold coins weigh 1.1 oz per coin while the fake coins weigh 1.0 oz each. You have a very accurate scale, but are allowed just one weighing. How do you determine the bag of real gold coins for sure with just the one weighing?

You didnt actually mention that you could remove the coins from the bag and weigh them together or separately.

[pavyracer]

Gold has a specific gravity of about 19.3.

The specific gravity of pyrite (fool's gold) is about 5.

So you can't have identical coins and the gold one's weigh 4 times more than the fool's gold coins but their is only 10% difference in weight.

That means the bag with the gold coins has smaller coins.

You don't even have to weigh the bags.

All you have to do is shake the bags and you can tell from the sound which bag has smaller coins.

[gauchojake]

does this still work

[dlowilly]

Gold has a specific gravity of about 19.3.

The specific gravity of pyrite (fool's gold) is about 5.

So you can't have identical coins and the gold one's weigh 4 times more than the fool's gold coins but their is only 10% difference in weight.

That means the bag with the gold coins has smaller coins.

You don't even have to weigh the bags.

All you have to do is shake the bags and you can tell from the sound which bag has smaller coins.

[asiagambler]

Yes you got it. You took the same route that Ganch did, so I needed a little more explanation for it to sink in.

Another way to get the same answer is to take 1 coin from Bag 1, 2 coins from Bag 2, and 3 coins from Bag 3 --a total of six coins. If the scale reads 6.1 oz then the Gold was in Bag 1, 6.2 oz means Bag 2 had the gold and of course a 6.3 oz reading means Bag 3 had the gold coins (remember the gold coins are 1.1 oz instead of 1.0).Several people figured this out in one form or another. Sharp bunch here

You would not even need 3 coins from bag 3. Just 1 coin from Bag 1 and 2 coins from Bag 2 is enough

[Al Masters]

You would not even need 3 coins from bag 3. Just 1 coin from Bag 1 and 2 coins from Bag 2 is enough

He asked this question 12 years ago..we appreciate the quick response.

[dlowilly]

You would not even need 3 coins from bag 3. Just 1 coin from Bag 1 and 2 coins from Bag 2 is enough

True

[HedgeHog]

You would not even need 3 coins from bag 3. Just 1 coin from Bag 1 and 2 coins from Bag 2 is enough

True, a single weighing in this manner would also work. As I mentioned 12 years ago, several sharp posters solved this puzzle in different ways. The common denominator was to think outside the box (or bag as it were) and take coins out the bags to do the single weighing. I choose to take coins out of each bag (1 from bag 1, 2 from bag 2, and 3 from bag 3) for easier illustration.

[deeppckts]

Besides HH and Crusherr, I do not think there is anyone else on this site who could ever solve this.
Such is the massive decline in brain power on this forum over the years.

Handicappers think tank is now riddled with SYSTEMS, MARTINGALES and other trash the mods are not skilled enough to filter from something serious.

[BigdaddyQH]

This is a question that was featured on a Columbo Mystery back then. It is not rocket science.