The 12 steel balls puzzle is known as a logic test, a simple puzzle that doesn’t require any extraordinary math knowledge, but instead it tests the mind logic and the ability to analyze problems, that’s why it’s recommended for developers to test their logic and ability to see all possible solutions of a problem and choose the right route to go through.

The Puzzle

As you can tell from its name, the puzzle is about 12 steel balls, identical in almost everything, color, size and shape, but as for weight they are all identical except for one, which is different without knowing whether it’s a heavier or lighter ball, Now we have a balance scale that we can use for only three weighings to identify the different ball and whether it’s a heavier or a lighter ball.

It may sound simple but it’s not as simple as it sounds, you can find more about this puzzle, its history and some hints and tips to solve on Paul Harkins’s website, I created a PDF version of the same file for non-windows user as well.

The Solution

Naturally I won’t post the solution today with the puzzle, I prefer to keep it until next Saturday (a week from now), although your emails and comments are welcomed, comments with right solutions on this post will not show up before the solution date, so if you are really the type of person that like logic challenges and mind puzzles, give it a shot and I’m postitve you will enjoy it.

UPDATE: It seems that this is not the type of puzzles that encourage commenting, I didn’t get a single comment on this. Because of that I will not spoil the beauty of this here, if you gave up and didn’t find the solution contact me privately and I’ll send you the solution, in case I received a lot of requests then I will post the solution here.

UPDATE 2: Great news, I got the first right solution from a friend of mine, Iyad Kallas (aka GraYFoX), he nailed it down and it’s your turn now, I still don’t want to post the solution not to spoil the joy of solving it, so if you are still thinking about it, maybe it’s time to finish it..

Joe and Max decided to cook five cups of rice, Joe had put three of them where Max had put two, after the dinner was ready, their friend Charlie joined them, and all of them them had the same quantity of food (one third), after they finished their dinner and before Charlie left, he gave them $50 for his share, and now Joe and Max are confused on how they should divide this amount between them fairly.

UPDATE: It seems that either I don’t have enough users to reply to this puzzle or the users I got didn’t bother solving it :) in both cases here is the solution:

• Charlie paid $50 for his share of the meal, which is one third the full meal, from this we can conclude that the full meal price is $50 x 3 = $150.
• The meal consisted of 5 cups of rice, so each cup price is $150 / 5 = $30.
• Joe gave 3 cups of rice, that worth $30 x 3 = $90, but he had his one third part of the meal that worth $50, so he should get: $90 - $50 = $40.
• Max gave 2 cups of rice, that worth $30 x 2 = $60, but he had his one third part of the meal that worth $50, so he should get: $60 - $50 = $10. :)