[問題]GWD23-30...答案是不是有錯??

[k06922001]

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

Ans:C
不過我算是D....我是這樣算的...
至少有一本是paper..C(2,1)C(6,3)+兩本都是paper...C(2,2)C(6,2)=40+15=55....D
請問是答案有錯嘛???還是我哪裡有考慮不周詳??請指教....謝謝

[k06922001]

推一下.........希望大家可以幫幫忙...討論一下!!!
拜託拜託了～~

[iven9]

http://forum.chasedream.com/dispbbs.asp ... ID=&skin=1
這是在CD搜尋到的討論串，
大家一至認為答案明顯錯誤。