Johnny can read 10 pages of a book in 15 minutes. At this rate, about how many hours will it take him to read a book with 317 pages?
A.4
B.8
C.13
D.20
E.28

Gravel is being dumped from a conveyor belt at a rate of 25 ft3/min, and its coarseness is such that it forms a pile in the shape of a cone whose base diameter and height are always equal. how fast is the height of the pile increasing when the pile is 14 ft high? (round your answer to two decimal places.) ft/min