推 kira1116 : D 06/02 16:53
推 bb7889 : D......算了好久 06/02 17:40
推 anthony797 : 跪求詳解 06/02 21:56
推 tarantula : (8*7*6*5)/(8*7*6*5+8*2*7*1*4) 06/26 22:58
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
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