When Greenville State University decided to move its fine arts collection to a new library, it had to package the collection in 20-inch by 20-inch by 12-inch boxes. If the university pays $0.40 for every box, and if the university needs 2.16 million cubic inches to package the collection, what is the minimum amount the university must spend on boxes? Choose the correct choice:
A) $ 120 B) $ 180 C) $ 310 D) $ 450 E) $ 640

Rationale: "the volume of each box is 20 * 20 * 12 = 4800 cubic inches . number of boxes = 2 , 160,000 / 4800 = 450 boxes total cost = 450 × $ 0.4 = $ 180 the answer is b ."
Answer: B