（1）当它第四次着地时总路程=100+50+50+25+25+12.5+12.5+6.25=281.25米
（2） 总路程为 100+50+25+12.5···························100/2^(n-1)
50+25+12.5+6.5·····························50/2^(n-1)
两个等比数列之和 当n趋于无穷大时上边的数列和比下边的数列和多100
对于下边的数列
Sn=A1(1-q^n)/(1-q) =50(1-(1/2)^n)/(1-1/2)
当n趋于无穷大时Sn=50/(1/2)=100
当n趋于无穷大时总路程 2Sn+100=300
所以：它到落地静止时所经过的路程不超过300米