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标题: gwd-24上一道题，答案是否有误？ [打印本页]

作者: katrinaxy520 时间: 2008-9-28 18:21
标题: gwd-24上一道题，答案是否有误？

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

答案选Ｃ，可是我算的是Ｄ，很简单的一道组合题啊．．．难道是我想错了？

请教ＮＮ！

作者: achine 时间: 2008-9-28 19:00
答案错了

作者: skb1109 时间: 2008-9-28 23:47

C(8,4)-C(6,4)=55

答案错了~~~

作者: katrinaxy520 时间: 2008-9-28 23:55
谢谢啦！我还以为是自己出了问题．

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