[u]Solution[/u] [spoiler]You divide them into a group of 6 balls and a group of 2 balls. You weigh the 6 first. 3 left & and 3 right. Suppose the weight isn't equal you take two from the heavier group and weigh them again. If it's equal it's the remaining one. If not you already found it. If the weight from the 3/3 weighing is equal you take the two remaining ones and weigh them. One has to be the heavier one.[/spoiler]