9 Marbles 3.0
Logic
Level
1
There are 9 marbles. They all weigh the same except for one, it weighs more. You are allowed to use a weighing scale twice. How do you figure out which one weighs more? What is the order you put the marbles in each time?
5,2,2
4,1,4
2,5,5
1,4,4
3,3,3
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1 solution
You weigh the two sets of three on either side, leaving out a final set of three aside. If one weighs more, you use only that three. Put one on each and if they weigh the same it is the one left out of that three. If one weighs more it is that one.
Lets say they are A,B,C - D,E,F - G,H,I
We put A,B,C and D,E,F on either side. If one side weighs more then the heavier marble is in that pile. In this case, just for arguments sake, they both weigh the same. The heavier marble will lie in G,H,I. So we put G one on side and H on the other. They weigh the same. It is I. You could use this technique for any 9 marbles with one weighing more.