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Q30:? There are 8 books on a shelf, of which 2 are paperbacks and 6 are hardbacks. How many possible selections of 4 books from this self include at least one paperback?
A. 40 B. 45 C. 50 D. 55 E. 60 我 算出来答案是D,正确答案是C A shipment of 8 television sets contains 2 black-and-white sets and 6color sets. If 2 television sets are to be chosen at random from this shipment, what is the probability that at least 1 of the 2 sets chosen will be a black-and-white set? A. 1/7 B. ¼ C. 5/14 D. 11/28 E. 13/26 我算出来答案是13/28, 给的答案是E
这两道题是我算错了吗？请大家帮我算算 | 
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发表于 2009-7-17 22:32:00
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