It's not at all clear what you mean by "by the 4th bounce". Here is the distance the ball has traveled, each time it goes down then up. You decide when to stop. 1. Goes down 100m. The ball has traveled 100m. Hits the ground the 1st time. 2. Goes up 60% of 100m, or 60m. The ball has traveled 160m. 3. Goes down 60m. The ball has traveled 220m. Hits the ground the 2nd time. 4. Goes up 60% of 60m, or 36m. The ball has traveled 256m. 5. Goes down 36m. The ball has traveled 292m. Hits the ground the 3rd time. 6. Goes up 60% of 36m, or 21.6m. The ball has traveled 313.6m. 7. Goes down 21.6m. The ball has traveled 335.2m. Hits the ground the 4th time. 8. Goes up 60% of 21.6m, or 12.96m. The ball has traveled 348.16m. 9. Goes down 12.6m. The ball has traveled 361.12m. Hits the ground the 5th time. When it hits the ground the 5th time it has traveled 361.12m If that's what you mean by "by the 4th bounce", that's the answer. If you mean when it hits the ground the 4th time, the answer is 335.2m If you mean when it rises to its highest point after hitting the ground the 4th time, the answer is 313.6m. Edwin