Quote:
Originally Posted by Chancie
My students obsessed about this problem today.
How would you solve it?
You have 100 valuable coins.
Well, one of the coins is counterfeit, so it’s not as valuable.
It’s either lighter or heavier than the genuine coins.
The only tool you have is a balance scale, and you have to pay a fee each time you use it.
How will you find the counterfeit coin?
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Okay, I'm probably going to show my ass here but I'm going to respond before I read anyone's responses:
I would take the coins, divide them into four equal groups then compare G-1, G-2, G-3 and G-4.
First iteration: compare G-1 and G-2. If equal then go to second iteration.
Second iteration: compare G-3 and G-4 at this point ONE of the piles will be unequal because the conterfeit coin has to be in one of those groups.
That's the most elegant solution I can come up with--at least while I wait for the coffee to finish brewing.