Scales question. What is the answer?

[T0 Th3 M4X]

There's an alternate way to solve the original problem.

You can weigh them 3vs3. If the heavier ball is in one of those two groups in will tip the scale to that side, then you work from that group of 3.  If it's not, you know it's one of the remaining 2 balls.  So you can actually get it in two if it happens to be in the set of two, but no more than 3 if it isn't.

Good thinking.

Thank you sir.

There's actually an alternate to this question.  Instead of stating that the ball is heavier, you can ask if the weight is different, but not specified as higher or lower.  You just can't use too many versions or someone will end up slapping you silly.