Question

three bells ring at an interval of 10,15 and 20 minutes respectively. If they ring at 10 am at once, what time they again ring together? Explain step by step plz

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Answer 1

Step-by-step explanation:

In 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.

Answer 2

Answer:

Step-by-step explanation:

Lcm of 10,15,20 mins = 1 hour or 60 mins. So the bell will ring at 11 am