[計量] 挑戰GRE計量170之二

看板GRE作者 (erichyu)時間10年前 (2015/06/02 16:12), 編輯推噓4(400)
留言4則, 4人參與, 最新討論串1/1
大家好,我是經典美語教授GRE計量的徐毓駿老師, 歡迎準備GRE考試的同學來試試以下這道題目: Two counterfeit coins of equal weight are mixed with 8 identical genuine coins. The weight of each of the counterfeit coins is different from the weight of each of the genuine coins. A pair of coins is selecd at random without replacement from the 10 coins. A second pair is selected at random without replacement from the remaining 8 coins. The combind weight of the first pair is equal to the combined weight of the second pair. What is the probability that all 4 selected coins are genuin? (A) 7/11 (B) 9/13 (C) 11/15 (D) 15/19 (E) 15/16 -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 59.115.241.197 ※ 文章網址: https://www.ptt.cc/bbs/GRE/M.1433232726.A.AE5.html

06/02 16:53, , 1F
D
06/02 16:53, 1F

06/02 17:40, , 2F
D......算了好久
06/02 17:40, 2F

06/02 21:56, , 3F
跪求詳解
06/02 21:56, 3F

06/26 22:58, , 4F
(8*7*6*5)/(8*7*6*5+8*2*7*1*4)
06/26 22:58, 4F
文章代碼(AID): #1LRMLMhb (GRE)