Five bells start ringing simultaneously and then continue to ring at intervals of 5, 10, 15, 20, and 25 seconds respectively. After how much time will they all ring together again?

Explanation

The bells ring together at intervals equal to the least common multiple (LCM) of their individual intervals: 5, 10, 15, 20, and 25 seconds. The LCM of these numbers is 300 seconds, which equals 5 minutes. Therefore, all the bells will toll together again after 5 minutes.