Water is poured into a tank so that the tank is being filled at the rate of 4 cubic feet per hour. If the empty rectangular tank is 6 feet long, 4 feet wide, and 3 feet deep, approximately how many hours does it take to fill the tank?	Choose the correct choice: A) 16 B) 18 C) 20 D) 22 E) 24

Rationale: "the volume the tank is : length * width * depth = 6 * 4 * 3 = 72 cubic feet . 72 cubic feet / 4 cubic feet per hour = 18 hours . it will take 18 hours to fill the tank . the answer is b ."
Answer: B