哪一位帮忙在电脑上算一下，给个精确答案

If it is a paper test and calculator is NOT permitted, we still can easily prove the chance is >90%.

364/365<365/366, 363/365<365/367,...,341/365<365/389

Thus,(316/365)*...*(365/365)<(316*...340)/(365*...*389)=(316/365)*(317/366)*...*(340/389)

Since 340/389<343/392=7/8, the chance is bigger than 1-(7/8)^25. lg(7/8)=0.844-0.902=-0.58
(7/8)^25 is about 10^(-0.058*25)=10^(-1.45)<0.1

所有跟帖： 

• 回复：哪一位帮忙在电脑上算一下，给个精确答案 -月明人倚楼- ♂ (313 bytes) () 01/15/2009 postreply 08:44:31

• 可以估算 -乱弹- ♂ (0 bytes) () 01/15/2009 postreply 18:28:32

• 可以估算。 -乱弹- ♂ (95 bytes) () 01/15/2009 postreply 18:34:04