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 True coins, fake coins (Posted on 2008-10-23)
You have eight bags, each of them containing 48 coins.

Five of these bags contain only true coins, the rest of them contain fake coins. Fake coins weigh 1 gram less than the real coins.

You do not know what bags have fake coins and what bags have real coins. You do not know also, besides that it is an integer value, the weight of the real coins.

You can use a digital or analog reading scale with precision up to 1 gram.

Making only one weighing and using the minimum number of coins, how can you find the bags containing the fake coins?

 See The Solution Submitted by pcbouhid Rating: 5.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
 re: really? | Comment 8 of 9 |
(In reply to really? by joe)

With the number from each bag being the set

1  2  3  4  7  12  21  38

A total grams short equal to 12  could be bags 2  3  5  or   1  4  5.
A total grams short equal to  17  could be bags 2  3  6  or   1  4  6.
A total grams short equal to  26  could be bags 2  3  7  or   1  4  7.
A total grams short equal to  43  could be bags 2  3  8  or   1  4  8.

Edited on February 27, 2013, 2:26 pm
 Posted by Charlie on 2013-02-27 14:24:32

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