Question

three bells ring with a time gap of 10 min,20 min and 30 min respectively in a school. if all bells are rung together at 8:00 am then after how long the bells would ring together again? step by step ​

Answer 1

Answer:

simple way, we need to find the lowest number, which is fully divisible bh 10, 15 and 20. So let's find the PCM of these 3, and that is 60mins.

So 60 minutes after 12 o'clock, all 3 bells will ring together again, ie at 1 o'clock.

Another way, non math way, to solve this is

BellA will ring at 12:00, 12:10, 12:20, 12:30, 12:40, 12:50, 1:00

BellB will ring at 12:00, 12:15, 12:30, 12:45, 1:00

BellC will ring at 12:00, 12:20, 12:40, 1:00

So, after ringing together at 12 o'clock, the bells will again ring together at 1 o'clock.