回複：我們班四月出生的特別多，占1/5。全班35人，

B(5,2;1/30)=C(5,2)*(1/30)^2*(1-1/30)^3=0.01
Happy birthday to you,my daughter's also in April.Summer is parent' happy days,So...四月出生的特別多.

所有跟帖： 

• 覺得應該比這個數字要大，大很多。 -金屬米- ♂ (0 bytes) () 04/23/2010 postreply 10:49:28

• 0.27,B is so,so.In fact,I can't do fast as young man -jinjing- ♀ (376 bytes) () 04/23/2010 postreply 13:10:35

• Please read my answer ,chang 5 to 7,ha ,too careless -jinjing- ♀ (0 bytes) () 04/23/2010 postreply 13:25:14

• Sorry ,It shout be 0.3, I for get *30 -jinjing- ♀ (0 bytes) () 04/23/2010 postreply 10:58:15

• wrong -jinjing- ♀ (0 bytes) () 04/23/2010 postreply 15:20:09

• 29.6266667% -曉仁悟- ♂ (0 bytes) () 05/05/2010 postreply 20:02:22

• 53.1% -曉仁悟- ♂ (41 bytes) () 05/05/2010 postreply 20:28:19

• 夏天精子較為活躍 -吹縐一池春水- ♀ (0 bytes) () 08/12/2010 postreply 12:57:21