Marbles...?

Question

Given are 12 marbles. One of these marbles is slightly heavier or lighter than the others. You have a two plate scale. You are allowed to weigh three times.
Can you find the marble that differs in weight?

Answer 1

6 on one side, 6 on the other. Take the 6 that weigh more, and divide them into 2 groups of 3. Weigh each group of 3. Take the heavier set and weigh 2 of them. If one is heavier, you have your answer. If they are the same, then the third that was excluded from the last weighing is the heavier one.

Answer 2

1. Separate the marbles into four different piles of three
2. Weigh two of the groups of marbles
A. If they balance, put them aside and weigh the other two sets of marbles to find the heavier set to use in the next step.
B. If they don't balance, disregard the other 6 marbles, and take the group of 3 which weighs more for the next step.
3. At this point you hav a goup of 3 marbles and KNOW that one is heavier. So, pick any two of the three and put one on each side of the scale.
A. If they weigh the same you know that the one you haven't weighed yet is the heavy one.
B. If one is heavier, than that's the one you were looking for.
**This works the same way for a lighter one, too, if you have the common sense to figure it out from here. (That's really not supposed to sound like an insult, if it did, I'm sorry.)

Answer 3

1. Put six marbles on each side. Remove the lighter side.
2. Put three marbles on each side. Remove the lighter side.
3. Put... oh wait... SHOOT!!!!!!!!!!!

Answer 4

1. put six on each side
2. take out the lighter side
3. put 3 on each side
4. take out the lighter side
oh wait nevermind. i thought it was supposed to be heavier. but it said it could be lighter too. sorry =(

Answer 5

sure, just put three marbles on each side