12 Marbles Scale 3 Times

So now in 2 tries we can find out which grp has the ball with the diffe weight then in another 1 try we can find out the different ball correct me if am wrong guys.

12 marbles scale 3 times. Click here for the answer. To do this put 3 marbles in each side 3 left 3 right 3 unused if the scale tips to a side we know that group of 3 has the heavy marble. So we need to begin the tedious task of mapping each result to an outcome. So that the plan can be followed let us number the marbles from 1 to 12.

There are two possibilities. Weigh 3 vs 4 if they balance then 8 is the odd light ball or the heaviest of 3 vs 4 is the. You can perform up to a maximum of three weighings to find out which marble has the different weight and if it is heavier or lighter than the others. Keep the heavy group of 3 marbles and discard the rest.

You don t know if that one is heavier or lighter. You are allowed to use the scales three times if you wish but no more. They all weigh the same except one. Split the marbles into 3 groups with 4 marbles each.

This gives you a total of 3 3 27 possible outcomes and in this case you need to discern 24 results from them one of 12 balls is either light or heavy which is 12 2 24. If the 2 groups weigh the same the heavier marble is in the 3rd group. If it does not tip to a side if it balances we know the unused group of 3 contains the heavy marble. Note that the unusual marble may be heavier or lighter than the others.

Your task is to identify the unusual marble and discard it. Once the group is determined split the marbles into 2 groups with 2 marbles each. If they are equal then you know that the different ball is lighter and is 1 of the 3 not weighed. The 12 marbles appear to be identical.

You have a balance scale. Next take 3 of the normal balls and 1 from the heavier group and weigh against the 1 ball from the lighter group plus the 3 balls you just replaced from the heavier group 2nd weighing. If 1 2 3 4 5 6 7 8 then either 1 2 3 4 contains a heavy ball or 5 6 7 8 contains a light ball so weigh 5 6 1 vs 7 2 12 with 3 possible outcomes. Either they balance or they don t.

If they balance then the different marble is in the group 9 10 11 12. If 5 6 1 vs 7 2 12 balances then either 8 is the odd light ball or 3 or 4 is the odd heavy ball. Lets split them into 4 grps of 3 each a 1 2 3 b 4 5 6 c 7 8 9 d 10 11 12 then weigh a against b and c vs d. You have 12 marbles.