There are 7 books on a shelf, of which 2 are paperbacks and 5 are hardbacks. How many possible selections of 4 books from this shelf include at least one paperback?  Select.
A) 30	B) 45	C) 50	D) 55	E) 60

Rationale: "approach 1 at - least 1 paper back = total - no paper back 7 c 4 - 5 c 4 = 30 approach 2 at - least 1 paper back = 1 paper back , 3 hard back or 2 paper back 2 hard back = 2 c 1 * 5 c 3 + 2 c 2 * 5 c 2 = 30 answer is a"
Answer: A