0
Four bells toll at intervals of 5, 10, 12 and 15 minutes respectively. If they start tolling together at 3, after what interval will they toll together and how many time they toll together in 18 hours?
- A2 hours, 9 times
- B3 hours, 6 times
- C30 minutes, 36 times
- D1 hour, 18 times
Correct answer: D