There are 8 books in a shelf that consist of 1 paperback books and 7 hardback books. If 4 books are selected at random without replacement, how many different combinations are there that at least one paperback book is selected?
Options:
(A) 35
(B) 45
(C) 50
(D) 55
(E) 60 Now, let's think a bit. Some random thoughts:
8C4 [Select any four] - 7C4 [Select all hard backs] = 35.
The final answer: (A).