The well is 4.5 meters deep, which is 450 cm. In each jump cycle, the frog effectively gains 30 cm - 15 cm = 15 cm in height. If we divide the total depth by the net progress per jump (450 cm / 15 cm), we get 30. However, on the final jump, when the frog reaches or surpasses the top edge, it does not slide back down. Therefore, we need to consider the point where the frog's jump would get it out of the well. The frog needs to reach a height from which a 30 cm jump will clear the well's edge. This means it needs to reach at least 450 cm - 30 cm = 420 cm through net progress. The number of jumps to reach 420 cm at a net gain of 15 cm per jump is 420/15 = 28 jumps. After these 28 jumps, the frog is at 420 cm. The next jump, the 29th jump, will take it 30 cm higher, reaching 450 cm, and it will be out of the well.