單發天弓三攔截機率百分之70
三發天弓三攔截機率為
一發攔截成功 兩發失敗機率
3×0.7×0.3×0.3
兩發攔截成功 一發失敗機率
3×0.7×0.7×0.3
三發攔截成功機率
0.7×0.7×0.7
3×0.7×0.3×0.3+3×0.7×0.7×0.3+0.7×0.7×0.7
=0.973