声明一下：草地是在雪山后但1/3不是雪山后的条件概率而是基于雪山前的人马

所有跟帖： 

• 为什么过草地要损失的人马不是按过草地之前，而是按过雪山之前？ -nnndayd- ♂ (221 bytes) () 01/13/2026 postreply 11:18:43

• 1/3 + (2/3) /2 = 2/3. -美国欧罗巴- ♂ (0 bytes) () 01/13/2026 postreply 11:23:54

• 是1/2+1/2*1/3 = 1/2+1/6 = 2/3 -蒋闻铭- ♂ (0 bytes) () 01/13/2026 postreply 11:36:52

• Delete -美国欧罗巴- ♂ (0 bytes) () 01/13/2026 postreply 11:52:34

• mean to crossing? -衡山老道- ♂ (0 bytes) () 01/13/2026 postreply 11:59:23

• 一方面军是先爬的雪山，后过的草地。：） -蒋闻铭- ♂ (0 bytes) () 01/13/2026 postreply 12:00:40

• Yes, you are correct. I thought he wanted to ask how -美国欧罗巴- ♂ (95 bytes) () 01/13/2026 postreply 12:03:17