You must have heard about the "12 coins" problem. Here this problem and many other varients have been analysed in full depth.

Here are some problems based on finding the defective coin from given coins. The defective coin may be lighter or heavier than other coins. You have to find the defective coin and its defect using a pan balance in certain number of chances.

Problem-1
Find the defective coin from 972 coins in 7 chances !!!

"Impossible !" you may say but it can be done. Try the next few problems and then come back to this one.

Problem-2
Find the defective coin from 12 coins in 3 chances.

This problem will take several minutes or even hours. If you don't get the answer then click the here.

Problem-3
Find the defective coin from 36 coins in 4 chances.

For this problem, problem-2 serves as a hint. If you don't get the answer then click here.

Problem-4
Find the defective coin from 108 coins in 5 chances.

Now you should be able to get that. Problems 2 and 3 are big hints.
Still I am giving the solution.

Problem-5
Find the defective coin from 324 coin in 6 chances.

Now I am not giving the solution. After you get the answer, go to first problem.


Back to main page