so i got 2 weighings at most.
1. Put 3 balls on one end and 3 on the other. the last 2 are left on the table.
2. If one group of 3 is heavier than the other, then you can outweigh 5 balls since the second group of 3 and the group of 2 are all the same weight. If the groups of 3 are equal in weight, then you know that one of the 2 balls in the unweighed group is heavier.
3. Put 2 balls on the scale (if one of the groups of 3 in part 2 was heavier, then put 2 of those balls on the scale, and leave one on the table again).
4. On the scale, pick the one that's heavier than the other. If, for the group of three, the balls are the same weight, then you know that the ball not on the scale will be heavier.

so i got 2 weighings at most.

1. Put 3 balls on one end and 3 on the other. the last 2 are left on the table.

2. If one group of 3 is heavier than the other, then you can outweigh 5 balls since the second group of 3 and the group of 2 are all the same weight. If the groups of 3 are equal in weight, then you know that one of the 2 balls in the unweighed group is heavier.

3. Put 2 balls on the scale (if one of the groups of 3 in part 2 was heavier, then put 2 of those balls on the scale, and leave one on the table again).

4. On the scale, pick the one that's heavier than the other. If, for the group of three, the balls are the same weight, then you know that the ball not on the scale will be heavier.

thanks for reading :>