Question

Three bells ring at an interval of 10,20,and 30 minutes respectively. If they all ring together at 10:30 p.m.,at what time will they again ring together?​

Answer 1

11:30 each number 10,20,30 have the common number of 60

Answer 2

11:30 PM

Explanation:

This question is essentially asking for the lowest common multiple of 10, 20, and 30. If we write out all the multiples of each, we get:

10: 10, 20, 30, 40, 50, 60, 70, ...

20: 20, 40, 60, 80, ...

30: 30, 60, 90, ...

As you can see, the lowest common multiple is 60, and 60 minutes after 10:30 PM is 11:30 PM.