Approximately how many cubic feet of water are needed to fill a circular swimming pool that is 100 feet across and 4 feet deep?	Choose the correct answer:
A) 15000 B) 30000 C) 50000 D) 70000 E) 90000

Rationale: "answer should be b . v = \ pir ^ 2 h = \ pi * 50 ^ 2 * 4 = approximately 30000"
Answer: B