Puzzle 5

[kunal naidu]

Hi all,

Here is another interesting puzzle

You have 100 bags full of many coins. All the coins in the bags are of 1 gram each. However, there is one bag which has coins weighing 2 grams each. You have a digital weighing machine. How can you find the bag with the 2 gram coins using the digital weighing machine once and only once? Assume that each bag has enough number of coins.

Have fun.

Regards

Kunal Naidu

Final Year Undergraduate

IIT Bombay

[aditi agarwal]

does each bag have equal no. of coins??

[bhuvan teja]

Take 1 coin from bag1, 2 coins from bag 2 and so on. Check the weight in the weighing machine.
Total weight=100(101)/2 + x. Where x is the bag which has coins of weight 2grams.

On Wed, Oct 12, 2011 at 12:19 PM, kunal naidu <kuna...@gmail.com> wrote:

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Bhuvan Teja

Junior Undergraduate | Computer Science & Engineering | IIT Bombay

[Sankalp Kelshikar]

Don't answer on the thread. Please.

Sankalp Kelshikar

[kunal naidu]

Hi all,

Each bag has many coins, we dont know how much....they may be the same in each bag or different.

P.S. Inspite of repeated requests, some people are still posting the solutions on the group or mailing them to me. Please dont do this, as this is not a competition. I will post the solutions on the group myself soon. Till that time, kindly give every1 a chance to attempt the problems.

Regards

Kunal Naidu

[bhuvan teja]

My bad. I apologize.

[kapil wanaskar]

@Kunal -
can u plz post d hint before u post d soln..

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Regards-
 Kapil Wanaskar
 Mechanical Engineering Department,
 Third Year DD student,
 IIT Bombay,
 Email - kapi...@gmail.com, kapil_w...@iitb.ac.in
 +91-9930255290

[Souvik Dutta]

If you still haven't looked at the solution, I'd propose the following hint. Since the number of coins aren't the same in each bag, you clearly can't work out your solution using bags, but individual coins. Also, since only 1 weighing is allowed, you need to "mark" the coins in some way to find out the odd bag out; This is possible in multiple ways.