一球从100米高处落下，每次落地后反跳回原高度的一半，再落下，求它在 　　　第10次落地时，共经过多少米？第10次反弹多高？-A ball dropped from 100 meters high, each counter after landing jumps back to half its original height, and then falls, find it at the 10th floor, a total of how many meters? 10th rebou