Three bells ring at intervals of 10 sec, 12 sec, and 15 sec respectively. If they start ringing together, how many times will they ring together in 5 hours?

Question: Three bells ring at intervals of 10 sec, 12 sec, and 15 sec respectively. If they start ringing together, how many times will they ring together in 5 hours?

Solution:
Given that,
Three bells ringing timing is 10 sec, 12 sec, and 15 sec
Now we have to take LCM of time interval ⇒ LCM of (10, 12, 15) = 60

Total seconds in 5 hours = 5 × 3600 = 18000

Number of times bell rings = 18000/60
⇒ Number of times bell rings = 300

If Three bells ring together in starting ⇒ 300 + 1
∴ The bell ringing 301 times in 5 hours.

Note: The bells start tolling together, the first toll also needs to be counted, that is the number of times of tolling since the first time.