Question

7. Four bell rings at interval of 10, 20 and 30 minutes respectively. At what time will

they again ring together if the rang together at 8 a.m.​

Answer 1

Answer:

1 o' clock

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:

Answer: 1o' clock

Step-by-step explanation:

This type of Question can be solved by finding HCF.