18 Aug 2022 5:02 am
Sorry, that is incorrect. I have already revealed that you start with 4x4, and then 3x3, and then 1x1.Skans » 11 Aug 2022, 2:19 am » wrote: ↑ I think I have the solution @RunningWithScissors :I am pretty sure this is the solution, unless I am missing something. Quite a nice little puzzle there!
- separate all 12 marbles into 4 groups of 3.
- First Weighing: weigh one 3 x 3 group - if they balance out then eliminate them; if they don't balance out, then switch a marble on one side with a marble on the other side (second weighing). If nothing changes, then eliminate those two marbles. If something does change, then your odd marble is one of those two and you can take one of those marbles and 3 from the balanced group to test to see if it is balanced or the odd one - either way, you will know what the other one is (3rd weighing)
- If in the First weighing they don't balance out, then you use the same procedure outlined above to find the odd marble. Still only requires 3 weighings.
The hard part is creating a control group, and moving marbles around to create new control groups as you go.