[問題] 請問一題數學

看板GMAT (GMAT入學考試)作者 (於是。)時間12年前 (2012/07/16 13:25), 編輯推噓0(000)
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A dog breeder currently has 9 breeding dogs. 6 of the dogs have exactly 1 littermate, and 3 of the dogs have exactly 2 littermates. If 2 dogs are selected at random, what is the probability that both selected dogs are NOT littermates? A. 1/6 B. 2/9 C. 5/6 D. 7/9 E. 8/9 想不出該怎麼組合才對呀! ="= -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 24.15.2.156
文章代碼(AID): #1G0wNSF6 (GMAT)
文章代碼(AID): #1G0wNSF6 (GMAT)