850 x 0.05 = 42.5
850 + 42.5 = 892.5
She earned 42.5
And 892.5 she wardens at the end of four years
It likely hit a barrier like a wall for example and the force of the ball hitting the wall caused it to be pushed away. Another possibility is that the ball was kicked up some sort of slop and when it was at the ten feet it slowed down and then rolled back down. I hope this helps.
Please see attached image with my answer.